From ade5ac3d6f50e4eec2210f0ad83e7b070794171a Mon Sep 17 00:00:00 2001
From: Niklas Baudy <niklas.baudy@vanniktech.de>
Date: Thu, 24 Nov 2016 10:14:24 +0100
Subject: [PATCH 1/3] Add CheckReturnValue method

---
 src/main/java/io/reactivex/Completable.java   |  3 ++
 src/main/java/io/reactivex/Flowable.java      |  4 +++
 src/main/java/io/reactivex/Maybe.java         |  3 ++
 src/main/java/io/reactivex/Observable.java    |  3 ++
 src/main/java/io/reactivex/Single.java        |  3 ++
 .../annotations/CheckReturnValue.java         | 33 +++++++++++++++++++
 6 files changed, 49 insertions(+)
 create mode 100644 src/main/java/io/reactivex/annotations/CheckReturnValue.java

diff --git a/src/main/java/io/reactivex/Completable.java b/src/main/java/io/reactivex/Completable.java
index 23a3839cb7..b58aa96b34 100644
--- a/src/main/java/io/reactivex/Completable.java
+++ b/src/main/java/io/reactivex/Completable.java
@@ -1555,6 +1555,7 @@ public final void subscribe(CompletableObserver s) {
      * @throws NullPointerException if {@code observer} is null
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E extends CompletableObserver> E subscribeWith(E observer) {
         subscribe(observer);
@@ -1871,6 +1872,7 @@ public final Completable unsubscribeOn(final Scheduler scheduler) {
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<Void> test() {
         TestObserver<Void> ts = new TestObserver<Void>();
@@ -1889,6 +1891,7 @@ public final TestObserver<Void> test() {
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<Void> test(boolean cancelled) {
         TestObserver<Void> ts = new TestObserver<Void>();
diff --git a/src/main/java/io/reactivex/Flowable.java b/src/main/java/io/reactivex/Flowable.java
index 92ad7ae1d6..1c70acc1ff 100644
--- a/src/main/java/io/reactivex/Flowable.java
+++ b/src/main/java/io/reactivex/Flowable.java
@@ -12266,6 +12266,7 @@ public final void subscribe(Subscriber<? super T> s) {
      * @throws NullPointerException if {@code subscriber} is null
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E extends Subscriber<? super T>> E subscribeWith(E subscriber) {
@@ -15303,6 +15304,7 @@ public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other,
      * @return the new TestSubscriber instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestSubscriber<T> test() { // NoPMD
@@ -15324,6 +15326,7 @@ public final TestSubscriber<T> test() { // NoPMD
      * @return the new TestSubscriber instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestSubscriber<T> test(long initialRequest) { // NoPMD
@@ -15347,6 +15350,7 @@ public final TestSubscriber<T> test(long initialRequest) { // NoPMD
      * @return the new TestSubscriber instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestSubscriber<T> test(long initialRequest, boolean cancel) { // NoPMD
diff --git a/src/main/java/io/reactivex/Maybe.java b/src/main/java/io/reactivex/Maybe.java
index 9804233003..99852baff6 100644
--- a/src/main/java/io/reactivex/Maybe.java
+++ b/src/main/java/io/reactivex/Maybe.java
@@ -3625,6 +3625,7 @@ public final Maybe<T> subscribeOn(Scheduler scheduler) {
      * @return the input {@code subscriber}
      * @throws NullPointerException if {@code subscriber} is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E extends MaybeObserver<? super T>> E subscribeWith(E observer) {
         subscribe(observer);
@@ -3954,6 +3955,7 @@ public final <U, R> Maybe<R> zipWith(MaybeSource<? extends U> other, BiFunction<
      * </dl>
      * @return the new TestObserver instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test() {
         TestObserver<T> ts = new TestObserver<T>();
@@ -3971,6 +3973,7 @@ public final TestObserver<T> test() {
      * Maybe.
      * @return the new TestObserver instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test(boolean cancelled) {
         TestObserver<T> ts = new TestObserver<T>();
diff --git a/src/main/java/io/reactivex/Observable.java b/src/main/java/io/reactivex/Observable.java
index 592bffc6c4..13138e6a35 100644
--- a/src/main/java/io/reactivex/Observable.java
+++ b/src/main/java/io/reactivex/Observable.java
@@ -10224,6 +10224,7 @@ public final void subscribe(Observer<? super T> observer) {
      * @throws NullPointerException if {@code observer} is null
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E extends Observer<? super T>> E subscribeWith(E observer) {
         subscribe(observer);
@@ -12872,6 +12873,7 @@ public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test() { // NoPMD
         TestObserver<T> ts = new TestObserver<T>();
@@ -12891,6 +12893,7 @@ public final TestObserver<T> test() { // NoPMD
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test(boolean dispose) { // NoPMD
         TestObserver<T> ts = new TestObserver<T>();
diff --git a/src/main/java/io/reactivex/Single.java b/src/main/java/io/reactivex/Single.java
index 0d41a7d8f4..2083171cb1 100644
--- a/src/main/java/io/reactivex/Single.java
+++ b/src/main/java/io/reactivex/Single.java
@@ -2596,6 +2596,7 @@ public final void subscribe(SingleObserver<? super T> subscriber) {
      * @throws NullPointerException if {@code observer} is null
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E extends SingleObserver<? super T>> E subscribeWith(E observer) {
         subscribe(observer);
@@ -2946,6 +2947,7 @@ public final <U, R> Single<R> zipWith(SingleSource<U> other, BiFunction<? super
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test() {
         TestObserver<T> ts = new TestObserver<T>();
@@ -2964,6 +2966,7 @@ public final TestObserver<T> test() {
      * @return the new TestObserver instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final TestObserver<T> test(boolean cancelled) {
         TestObserver<T> ts = new TestObserver<T>();
diff --git a/src/main/java/io/reactivex/annotations/CheckReturnValue.java b/src/main/java/io/reactivex/annotations/CheckReturnValue.java
new file mode 100644
index 0000000000..0af6b90a78
--- /dev/null
+++ b/src/main/java/io/reactivex/annotations/CheckReturnValue.java
@@ -0,0 +1,33 @@
+/**
+ * Copyright 2016 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is
+ * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
+ * the License for the specific language governing permissions and limitations under the License.
+ */
+
+package io.reactivex.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks methods whose return values should be checked.
+ * 
+ * @since 2.0.2 - experimental
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Target(ElementType.METHOD)
+@Experimental
+public @interface CheckReturnValue {
+
+}

From ddc88e5e2d6a62e5d2e5071cac1bb86a2dc16264 Mon Sep 17 00:00:00 2001
From: Niklas Baudy <niklas.baudy@vanniktech.de>
Date: Thu, 24 Nov 2016 15:32:43 +0100
Subject: [PATCH 2/3] Add annotation to more methods

---
 src/main/java/io/reactivex/Completable.java   |  90 ++++
 src/main/java/io/reactivex/Flowable.java      | 438 +++++++++++++++++-
 src/main/java/io/reactivex/Maybe.java         | 153 +++++-
 src/main/java/io/reactivex/Observable.java    | 423 ++++++++++++++++-
 src/main/java/io/reactivex/Single.java        | 113 +++++
 .../annotations/CheckReturnValue.java         |   2 +-
 .../io/reactivex/BaseTypeAnnotations.java     |  73 ++-
 7 files changed, 1283 insertions(+), 9 deletions(-)

diff --git a/src/main/java/io/reactivex/Completable.java b/src/main/java/io/reactivex/Completable.java
index b58aa96b34..e028649a3d 100644
--- a/src/main/java/io/reactivex/Completable.java
+++ b/src/main/java/io/reactivex/Completable.java
@@ -50,6 +50,7 @@ public abstract class Completable implements CompletableSource {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable ambArray(final CompletableSource... sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -74,6 +75,7 @@ public static Completable ambArray(final CompletableSource... sources) {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable amb(final Iterable<? extends CompletableSource> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -89,6 +91,7 @@ public static Completable amb(final Iterable<? extends CompletableSource> source
      * </dl>
      * @return a Completable instance that completes immediately
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable complete() {
         return RxJavaPlugins.onAssembly(CompletableEmpty.INSTANCE);
@@ -104,6 +107,7 @@ public static Completable complete() {
      * @return the Completable instance which completes only when all sources complete
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable concatArray(CompletableSource... sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -126,6 +130,7 @@ public static Completable concatArray(CompletableSource... sources) {
      * @return the Completable instance which completes only when all sources complete
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable concat(Iterable<? extends CompletableSource> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -146,6 +151,7 @@ public static Completable concat(Iterable<? extends CompletableSource> sources)
      * @return the Completable instance which completes only when all sources complete
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     public static Completable concat(Publisher<? extends CompletableSource> sources) {
@@ -166,6 +172,7 @@ public static Completable concat(Publisher<? extends CompletableSource> sources)
      * @return the Completable instance which completes only when all sources complete
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     public static Completable concat(Publisher<? extends CompletableSource> sources, int prefetch) {
@@ -208,6 +215,7 @@ public static Completable concat(Publisher<? extends CompletableSource> sources,
      * @see CompletableOnSubscribe
      * @see Cancellable
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable create(CompletableOnSubscribe source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -227,6 +235,7 @@ public static Completable create(CompletableOnSubscribe source) {
      * @return the created Completable instance
      * @throws NullPointerException if source is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable unsafeCreate(CompletableSource source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -245,6 +254,7 @@ public static Completable unsafeCreate(CompletableSource source) {
      * @param completableSupplier the supplier that returns the Completable that will be subscribed to.
      * @return the Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable defer(final Callable<? extends CompletableSource> completableSupplier) {
         ObjectHelper.requireNonNull(completableSupplier, "completableSupplier");
@@ -265,6 +275,7 @@ public static Completable defer(final Callable<? extends CompletableSource> comp
      * @return the new Completable instance
      * @throws NullPointerException if errorSupplier is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable error(final Callable<? extends Throwable> errorSupplier) {
         ObjectHelper.requireNonNull(errorSupplier, "errorSupplier is null");
@@ -281,6 +292,7 @@ public static Completable error(final Callable<? extends Throwable> errorSupplie
      * @return the new Completable instance
      * @throws NullPointerException if error is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable error(final Throwable error) {
         ObjectHelper.requireNonNull(error, "error is null");
@@ -299,6 +311,7 @@ public static Completable error(final Throwable error) {
      * @return the new Completable instance
      * @throws NullPointerException if run is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable fromAction(final Action run) {
         ObjectHelper.requireNonNull(run, "run is null");
@@ -315,6 +328,7 @@ public static Completable fromAction(final Action run) {
      * @param callable the callable instance to execute for each subscriber
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable fromCallable(final Callable<?> callable) {
         ObjectHelper.requireNonNull(callable, "callable is null");
@@ -332,6 +346,7 @@ public static Completable fromCallable(final Callable<?> callable) {
      * @param future the future to react to
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable fromFuture(final Future<?> future) {
         ObjectHelper.requireNonNull(future, "future is null");
@@ -349,6 +364,7 @@ public static Completable fromFuture(final Future<?> future) {
      * @return the new Completable instance
      * @throws NullPointerException if run is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable fromRunnable(final Runnable run) {
         ObjectHelper.requireNonNull(run, "run is null");
@@ -367,6 +383,7 @@ public static Completable fromRunnable(final Runnable run) {
      * @return the new Completable instance
      * @throws NullPointerException if flowable is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Completable fromObservable(final ObservableSource<T> observable) {
         ObjectHelper.requireNonNull(observable, "observable is null");
@@ -388,6 +405,7 @@ public static <T> Completable fromObservable(final ObservableSource<T> observabl
      * @return the new Completable instance
      * @throws NullPointerException if publisher is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Completable fromPublisher(final Publisher<T> publisher) {
@@ -407,6 +425,7 @@ public static <T> Completable fromPublisher(final Publisher<T> publisher) {
      * @return the new Completable instance
      * @throws NullPointerException if single is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Completable fromSingle(final SingleSource<T> single) {
         ObjectHelper.requireNonNull(single, "single is null");
@@ -424,6 +443,7 @@ public static <T> Completable fromSingle(final SingleSource<T> single) {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable mergeArray(CompletableSource... sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -447,6 +467,7 @@ public static Completable mergeArray(CompletableSource... sources) {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable merge(Iterable<? extends CompletableSource> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -467,6 +488,7 @@ public static Completable merge(Iterable<? extends CompletableSource> sources) {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     public static Completable merge(Publisher<? extends CompletableSource> sources) {
@@ -489,6 +511,7 @@ public static Completable merge(Publisher<? extends CompletableSource> sources)
      * @throws NullPointerException if sources is null
      * @throws IllegalArgumentException if maxConcurrency is less than 1
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     public static Completable merge(Publisher<? extends CompletableSource> sources, int maxConcurrency) {
@@ -513,6 +536,7 @@ public static Completable merge(Publisher<? extends CompletableSource> sources,
      * @throws NullPointerException if sources is null
      * @throws IllegalArgumentException if maxConcurrency is less than 1
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     private static Completable merge0(Publisher<? extends CompletableSource> sources, int maxConcurrency, boolean delayErrors) {
@@ -533,6 +557,7 @@ private static Completable merge0(Publisher<? extends CompletableSource> sources
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable mergeArrayDelayError(CompletableSource... sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -551,6 +576,7 @@ public static Completable mergeArrayDelayError(CompletableSource... sources) {
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable mergeDelayError(Iterable<? extends CompletableSource> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -573,6 +599,7 @@ public static Completable mergeDelayError(Iterable<? extends CompletableSource>
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     public static Completable mergeDelayError(Publisher<? extends CompletableSource> sources) {
@@ -596,6 +623,7 @@ public static Completable mergeDelayError(Publisher<? extends CompletableSource>
      * @return the new Completable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     public static Completable mergeDelayError(Publisher<? extends CompletableSource> sources, int maxConcurrency) {
@@ -610,6 +638,7 @@ public static Completable mergeDelayError(Publisher<? extends CompletableSource>
      * </dl>
      * @return the singleton instance that never calls onError or onComplete
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable never() {
         return RxJavaPlugins.onAssembly(CompletableNever.INSTANCE);
@@ -625,6 +654,7 @@ public static Completable never() {
      * @param unit the delay unit
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Completable timer(long delay, TimeUnit unit) {
         return timer(delay, unit, Schedulers.computation());
@@ -642,6 +672,7 @@ public static Completable timer(long delay, TimeUnit unit) {
      * @param scheduler the scheduler where to emit the complete event
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Completable timer(final long delay, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -675,6 +706,7 @@ private static NullPointerException toNpe(Throwable ex) {
      * @param disposer the consumer that disposes the resource created by the resource supplier
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <R> Completable using(Callable<R> resourceSupplier,
             Function<? super R, ? extends CompletableSource> completableFunction,
@@ -702,6 +734,7 @@ public static <R> Completable using(Callable<R> resourceSupplier,
      * resource is disposed after the terminal event has been emitted
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <R> Completable using(
             final Callable<R> resourceSupplier,
@@ -726,6 +759,7 @@ public static <R> Completable using(
      * @return the source or its wrapper Completable
      * @throws NullPointerException if source is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Completable wrap(CompletableSource source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -746,6 +780,7 @@ public static Completable wrap(CompletableSource source) {
      * @return the new Completable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable ambWith(CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -766,6 +801,7 @@ public final Completable ambWith(CompletableSource other) {
      * @return Observable that composes this Completable and next
      * @throws NullPointerException if next is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Observable<T> andThen(ObservableSource<T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -789,6 +825,7 @@ public final <T> Observable<T> andThen(ObservableSource<T> next) {
      * @return Flowable that composes this Completable and next
      * @throws NullPointerException if next is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Flowable<T> andThen(Publisher<T> next) {
@@ -810,6 +847,7 @@ public final <T> Flowable<T> andThen(Publisher<T> next) {
      * @param next the Single to subscribe after this Completable is completed, not null
      * @return Single that composes this Completable and next
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Single<T> andThen(SingleSource<T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -830,6 +868,7 @@ public final <T> Single<T> andThen(SingleSource<T> next) {
      * @param next the Maybe to subscribe after this Completable is completed, not null
      * @return Maybe that composes this Completable and next
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Maybe<T> andThen(MaybeSource<T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -849,6 +888,7 @@ public final <T> Maybe<T> andThen(MaybeSource<T> next) {
      * @return the new Completable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable andThen(CompletableSource next) {
         return concatWith(next);
@@ -883,6 +923,7 @@ public final void blockingAwait() {
      * false if the timeout elapsed before this Completable terminated.
      * @throws RuntimeException wrapping an InterruptedException if the current thread is interrupted
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final boolean blockingAwait(long timeout, TimeUnit unit) {
         BlockingMultiObserver<Void> observer = new BlockingMultiObserver<Void>();
@@ -900,6 +941,7 @@ public final boolean blockingAwait(long timeout, TimeUnit unit) {
      * @return the throwable if this terminated with an error, null otherwise
      * @throws RuntimeException that wraps an InterruptedException if the wait is interrupted
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Throwable blockingGet() {
         BlockingMultiObserver<Void> observer = new BlockingMultiObserver<Void>();
@@ -920,6 +962,7 @@ public final Throwable blockingGet() {
      * @throws RuntimeException that wraps an InterruptedException if the wait is interrupted or
      * TimeoutException if the specified timeout elapsed before it
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Throwable blockingGet(long timeout, TimeUnit unit) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -939,6 +982,7 @@ public final Throwable blockingGet(long timeout, TimeUnit unit) {
      * @return the Completable returned by the function
      * @throws NullPointerException if transformer is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable compose(CompletableTransformer transformer) {
         return wrap(transformer.apply(this));
@@ -954,6 +998,7 @@ public final Completable compose(CompletableTransformer transformer) {
      * @return the new Completable which subscribes to this and then the other Completable
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable concatWith(CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -971,6 +1016,7 @@ public final Completable concatWith(CompletableSource other) {
      * @return the new Completable instance
      * @throws NullPointerException if unit is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Completable delay(long delay, TimeUnit unit) {
         return delay(delay, unit, Schedulers.computation(), false);
@@ -989,6 +1035,7 @@ public final Completable delay(long delay, TimeUnit unit) {
      * @return the new Completable instance
      * @throws NullPointerException if unit or scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable delay(long delay, TimeUnit unit, Scheduler scheduler) {
         return delay(delay, unit, scheduler, false);
@@ -1008,6 +1055,7 @@ public final Completable delay(long delay, TimeUnit unit, Scheduler scheduler) {
      * @return the new Completable instance
      * @throws NullPointerException if unit or scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable delay(final long delay, final TimeUnit unit, final Scheduler scheduler, final boolean delayError) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -1025,6 +1073,7 @@ public final Completable delay(final long delay, final TimeUnit unit, final Sche
      * @return the new Completable instance
      * @throws NullPointerException if onComplete is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnComplete(Action onComplete) {
         return doOnLifecycle(Functions.emptyConsumer(), Functions.emptyConsumer(),
@@ -1043,6 +1092,7 @@ public final Completable doOnComplete(Action onComplete) {
      * @return the new Completable instance
      * @throws NullPointerException if onDispose is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnDispose(Action onDispose) {
         return doOnLifecycle(Functions.emptyConsumer(), Functions.emptyConsumer(),
@@ -1060,6 +1110,7 @@ public final Completable doOnDispose(Action onDispose) {
      * @return the new Completable instance
      * @throws NullPointerException if onError is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnError(Consumer<? super Throwable> onError) {
         return doOnLifecycle(Functions.emptyConsumer(), onError,
@@ -1078,6 +1129,7 @@ public final Completable doOnError(Consumer<? super Throwable> onError) {
      * @return the new Completable instance
      * @throws NullPointerException if onEvent is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnEvent(final Consumer<? super Throwable> onEvent) {
         ObjectHelper.requireNonNull(onEvent, "onEvent is null");
@@ -1098,6 +1150,7 @@ public final Completable doOnEvent(final Consumer<? super Throwable> onEvent) {
      * @param onDispose the runnable called when the child disposes the subscription
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     private Completable doOnLifecycle(
             final Consumer<? super Disposable> onSubscribe,
@@ -1126,6 +1179,7 @@ private Completable doOnLifecycle(
      * @return the new Completable instance
      * @throws NullPointerException if onSubscribe is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnSubscribe(Consumer<? super Disposable> onSubscribe) {
         return doOnLifecycle(onSubscribe, Functions.emptyConsumer(),
@@ -1143,6 +1197,7 @@ public final Completable doOnSubscribe(Consumer<? super Disposable> onSubscribe)
      * @param onTerminate the callback to call just before this Completable terminates
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doOnTerminate(final Action onTerminate) {
         return doOnLifecycle(Functions.emptyConsumer(), Functions.emptyConsumer(),
@@ -1160,6 +1215,7 @@ public final Completable doOnTerminate(final Action onTerminate) {
      * @param onAfterTerminate the callback to call after this Completable terminates
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable doAfterTerminate(final Action onAfterTerminate) {
         return doOnLifecycle(
@@ -1185,6 +1241,7 @@ public final Completable doAfterTerminate(final Action onAfterTerminate) {
      * @return the new Completable instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Completable doFinally(Action onFinally) {
@@ -1203,6 +1260,7 @@ public final Completable doFinally(Action onFinally) {
      * @return the new Completable instance
      * @throws NullPointerException if onLift is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable lift(final CompletableOperator onLift) {
         ObjectHelper.requireNonNull(onLift, "onLift is null");
@@ -1220,6 +1278,7 @@ public final Completable lift(final CompletableOperator onLift) {
      * @return the new Completable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable mergeWith(CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1236,6 +1295,7 @@ public final Completable mergeWith(CompletableSource other) {
      * @return the new Completable instance
      * @throws NullPointerException if scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable observeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -1251,6 +1311,7 @@ public final Completable observeOn(final Scheduler scheduler) {
      * </dl>
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable onErrorComplete() {
         return onErrorComplete(Functions.alwaysTrue());
@@ -1267,6 +1328,7 @@ public final Completable onErrorComplete() {
      * if the Throwable should be swallowed and replaced with an onComplete.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable onErrorComplete(final Predicate<? super Throwable> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -1286,6 +1348,7 @@ public final Completable onErrorComplete(final Predicate<? super Throwable> pred
      * continuation.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable onErrorResumeNext(final Function<? super Throwable, ? extends CompletableSource> errorMapper) {
         ObjectHelper.requireNonNull(errorMapper, "errorMapper is null");
@@ -1300,6 +1363,7 @@ public final Completable onErrorResumeNext(final Function<? super Throwable, ? e
      * </dl>
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable repeat() {
         return fromPublisher(toFlowable().repeat());
@@ -1315,6 +1379,7 @@ public final Completable repeat() {
      * @return the new Completable instance
      * @throws IllegalArgumentException if times is less than zero
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable repeat(long times) {
         return fromPublisher(toFlowable().repeat(times));
@@ -1331,6 +1396,7 @@ public final Completable repeat(long times) {
      * @return the new Completable instance
      * @throws NullPointerException if stop is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable repeatUntil(BooleanSupplier stop) {
         return fromPublisher(toFlowable().repeatUntil(stop));
@@ -1349,6 +1415,7 @@ public final Completable repeatUntil(BooleanSupplier stop) {
      * @return the new Completable instance
      * @throws NullPointerException if stop is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable repeatWhen(Function<? super Flowable<Object>, ? extends Publisher<Object>> handler) {
         return fromPublisher(toFlowable().repeatWhen(handler));
@@ -1362,6 +1429,7 @@ public final Completable repeatWhen(Function<? super Flowable<Object>, ? extends
      * </dl>
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable retry() {
         return fromPublisher(toFlowable().retry());
@@ -1378,6 +1446,7 @@ public final Completable retry() {
      * and should return true to retry.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable retry(BiPredicate<? super Integer, ? super Throwable> predicate) {
         return fromPublisher(toFlowable().retry(predicate));
@@ -1394,6 +1463,7 @@ public final Completable retry(BiPredicate<? super Integer, ? super Throwable> p
      * @return the new Completable instance
      * @throws IllegalArgumentException if times is negative
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable retry(long times) {
         return fromPublisher(toFlowable().retry(times));
@@ -1411,6 +1481,7 @@ public final Completable retry(long times) {
      * @return the new Completable instance
      * @throws NullPointerException if predicate is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable retry(Predicate<? super Throwable> predicate) {
         return fromPublisher(toFlowable().retry(predicate));
@@ -1429,6 +1500,7 @@ public final Completable retry(Predicate<? super Throwable> predicate) {
      * @return the new Completable instance
      * @throws NullPointerException if handler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable retryWhen(Function<? super Flowable<Throwable>, ? extends Publisher<Object>> handler) {
         return fromPublisher(toFlowable().retryWhen(handler));
@@ -1445,6 +1517,7 @@ public final Completable retryWhen(Function<? super Flowable<Throwable>, ? exten
      * @return the new Completable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable startWith(CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1463,6 +1536,7 @@ public final Completable startWith(CompletableSource other) {
      * @return the new Observable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Observable<T> startWith(Observable<T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1483,6 +1557,7 @@ public final <T> Observable<T> startWith(Observable<T> other) {
      * @return the new Flowable instance
      * @throws NullPointerException if other is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Flowable<T> startWith(Publisher<T> other) {
@@ -1573,6 +1648,7 @@ public final <E extends CompletableObserver> E subscribeWith(E observer) {
      * @return the Disposable that can be used for cancelling the subscription asynchronously
      * @throws NullPointerException if either callback is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(final Action onComplete, final Consumer<? super Throwable> onError) {
         ObjectHelper.requireNonNull(onError, "onError is null");
@@ -1595,6 +1671,7 @@ public final Disposable subscribe(final Action onComplete, final Consumer<? supe
      * @param onComplete the runnable called when this Completable completes normally
      * @return the Disposable that allows cancelling the subscription
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(final Action onComplete) {
         ObjectHelper.requireNonNull(onComplete, "onComplete is null");
@@ -1615,6 +1692,7 @@ public final Disposable subscribe(final Action onComplete) {
      * @return the new Completable instance
      * @throws NullPointerException if scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable subscribeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -1634,6 +1712,7 @@ public final Completable subscribeOn(final Scheduler scheduler) {
      * @return the new Completable instance
      * @throws NullPointerException if unit is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Completable timeout(long timeout, TimeUnit unit) {
         return timeout0(timeout, unit, Schedulers.computation(), null);
@@ -1653,6 +1732,7 @@ public final Completable timeout(long timeout, TimeUnit unit) {
      * @return the new Completable instance
      * @throws NullPointerException if unit or other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Completable timeout(long timeout, TimeUnit unit, CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1673,6 +1753,7 @@ public final Completable timeout(long timeout, TimeUnit unit, CompletableSource
      * @return the new Completable instance
      * @throws NullPointerException if unit or scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable timeout(long timeout, TimeUnit unit, Scheduler scheduler) {
         return timeout0(timeout, unit, scheduler, null);
@@ -1694,6 +1775,7 @@ public final Completable timeout(long timeout, TimeUnit unit, Scheduler schedule
      * @return the new Completable instance
      * @throws NullPointerException if unit, scheduler or other is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable timeout(long timeout, TimeUnit unit, Scheduler scheduler, CompletableSource other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1716,6 +1798,7 @@ public final Completable timeout(long timeout, TimeUnit unit, Scheduler schedule
      * @return the new Completable instance
      * @throws NullPointerException if unit or scheduler
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     private Completable timeout0(long timeout, TimeUnit unit, Scheduler scheduler, CompletableSource other) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -1734,6 +1817,7 @@ private Completable timeout0(long timeout, TimeUnit unit, Scheduler scheduler, C
      * @return the converted value
      * @throws NullPointerException if converter is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> U to(Function<? super Completable, U> converter) {
         try {
@@ -1756,6 +1840,7 @@ public final <U> U to(Function<? super Completable, U> converter) {
      * @param <T> the value type
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @SuppressWarnings("unchecked")
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
@@ -1778,6 +1863,7 @@ public final <T> Flowable<T> toFlowable() {
      * @param <T> the value type
      * @return a {@link Maybe} that emits a single item T or an error.
      */
+    @CheckReturnValue
     @SuppressWarnings("unchecked")
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Maybe<T> toMaybe() {
@@ -1797,6 +1883,7 @@ public final <T> Maybe<T> toMaybe() {
      * @param <T> the value type
      * @return the new Observable created
      */
+    @CheckReturnValue
     @SuppressWarnings("unchecked")
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Observable<T> toObservable() {
@@ -1818,6 +1905,7 @@ public final <T> Observable<T> toObservable() {
      * @return the new Single instance
      * @throws NullPointerException if completionValueSupplier is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Single<T> toSingle(final Callable<? extends T> completionValueSupplier) {
         ObjectHelper.requireNonNull(completionValueSupplier, "completionValueSupplier is null");
@@ -1836,6 +1924,7 @@ public final <T> Single<T> toSingle(final Callable<? extends T> completionValueS
      * @return the new Single instance
      * @throws NullPointerException if completionValue is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T> Single<T> toSingleDefault(final T completionValue) {
         ObjectHelper.requireNonNull(completionValue, "completionValue is null");
@@ -1853,6 +1942,7 @@ public final <T> Single<T> toSingleDefault(final T completionValue) {
      * @return the new Completable instance
      * @throws NullPointerException if scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Completable unsubscribeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
diff --git a/src/main/java/io/reactivex/Flowable.java b/src/main/java/io/reactivex/Flowable.java
index 1c70acc1ff..4c4cc601e3 100644
--- a/src/main/java/io/reactivex/Flowable.java
+++ b/src/main/java/io/reactivex/Flowable.java
@@ -82,6 +82,7 @@ public abstract class Flowable<T> implements Publisher<T> {
      *         emitted an item or sent a termination notification
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> amb(Iterable<? extends Publisher<? extends T>> sources) {
@@ -109,6 +110,7 @@ public static <T> Flowable<T> amb(Iterable<? extends Publisher<? extends T>> sou
      *         emitted an item or sent a termination notification
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> ambArray(Publisher<? extends T>... sources) {
@@ -164,6 +166,7 @@ public static int bufferSize() {
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatest(Publisher<? extends T>[] sources, Function<? super Object[], ? extends R> combiner) {
         return combineLatest(sources, combiner, bufferSize());
@@ -200,6 +203,7 @@ public static <T, R> Flowable<R> combineLatest(Publisher<? extends T>[] sources,
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatest(Function<? super Object[], ? extends R> combiner, Publisher<? extends T>... sources) {
         return combineLatest(sources, combiner, bufferSize());
@@ -238,6 +242,7 @@ public static <T, R> Flowable<R> combineLatest(Function<? super Object[], ? exte
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatest(Publisher<? extends T>[] sources, Function<? super Object[], ? extends R> combiner, int bufferSize) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -280,6 +285,7 @@ public static <T, R> Flowable<R> combineLatest(Publisher<? extends T>[] sources,
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatest(Iterable<? extends Publisher<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -319,6 +325,7 @@ public static <T, R> Flowable<R> combineLatest(Iterable<? extends Publisher<? ex
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatest(Iterable<? extends Publisher<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -359,6 +366,7 @@ public static <T, R> Flowable<R> combineLatest(Iterable<? extends Publisher<? ex
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Publisher<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -397,6 +405,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Publisher<? extends T>[
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Function<? super Object[], ? extends R> combiner,
             Publisher<? extends T>... sources) {
@@ -437,6 +446,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Function<? super Object
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Function<? super Object[], ? extends R> combiner,
             int bufferSize, Publisher<? extends T>... sources) {
@@ -477,6 +487,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Function<? super Object
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Publisher<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -521,6 +532,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Publisher<? extends T>[
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Iterable<? extends Publisher<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -561,6 +573,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Iterable<? extends Publ
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SchedulerSupport(SchedulerSupport.NONE)
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T, R> Flowable<R> combineLatestDelayError(Iterable<? extends Publisher<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -599,6 +612,7 @@ public static <T, R> Flowable<R> combineLatestDelayError(Iterable<? extends Publ
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Flowable<R> combineLatest(
@@ -642,6 +656,7 @@ public static <T1, T2, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, R> Flowable<R> combineLatest(
@@ -689,6 +704,7 @@ public static <T1, T2, T3, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, R> Flowable<R> combineLatest(
@@ -740,6 +756,7 @@ public static <T1, T2, T3, T4, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, R> Flowable<R> combineLatest(
@@ -796,6 +813,7 @@ public static <T1, T2, T3, T4, T5, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> combineLatest(
@@ -856,6 +874,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> combineLatest(
@@ -921,6 +940,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> combineLatest(
@@ -990,6 +1010,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> combineLatest(
@@ -1030,6 +1051,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> combineLatest(
      * @return the new Flowable instance
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Iterable<? extends Publisher<? extends T>> sources) {
@@ -1060,6 +1082,7 @@ public static <T> Flowable<T> concat(Iterable<? extends Publisher<? extends T>>
      *         {@code Publishers}, one after the other, without interleaving them
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Publisher<? extends Publisher<? extends T>> sources) {
@@ -1091,6 +1114,7 @@ public static <T> Flowable<T> concat(Publisher<? extends Publisher<? extends T>>
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Publisher<? extends Publisher<? extends T>> sources, int prefetch) {
@@ -1122,6 +1146,7 @@ public static <T> Flowable<T> concat(Publisher<? extends Publisher<? extends T>>
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Publisher<? extends T> source1, Publisher<? extends T> source2) {
@@ -1155,6 +1180,7 @@ public static <T> Flowable<T> concat(Publisher<? extends T> source1, Publisher<?
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(
@@ -1192,6 +1218,7 @@ public static <T> Flowable<T> concat(
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(
@@ -1220,6 +1247,7 @@ public static <T> Flowable<T> concat(
      * @return the new Publisher instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatArray(Publisher<? extends T>... sources) {
@@ -1251,6 +1279,7 @@ public static <T> Flowable<T> concatArray(Publisher<? extends T>... sources) {
      * @return the new Flowable instance
      * @throws NullPointerException if sources is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatArrayDelayError(Publisher<? extends T>... sources) {
@@ -1283,6 +1312,7 @@ public static <T> Flowable<T> concatArrayDelayError(Publisher<? extends T>... so
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatArrayEager(Publisher<? extends T>... sources) {
@@ -1312,6 +1342,7 @@ public static <T> Flowable<T> concatArrayEager(Publisher<? extends T>... sources
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
@@ -1338,6 +1369,7 @@ public static <T> Flowable<T> concatArrayEager(int maxConcurrency, int prefetch,
      * @return the new Publisher with the concatenating behavior
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatDelayError(Iterable<? extends Publisher<? extends T>> sources) {
@@ -1360,6 +1392,7 @@ public static <T> Flowable<T> concatDelayError(Iterable<? extends Publisher<? ex
      * @param sources the Publisher sequence of Publishers
      * @return the new Publisher with the concatenating behavior
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatDelayError(Publisher<? extends Publisher<? extends T>> sources) {
@@ -1385,6 +1418,7 @@ public static <T> Flowable<T> concatDelayError(Publisher<? extends Publisher<? e
      * @return the new Publisher with the concatenating behavior
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatDelayError(Publisher<? extends Publisher<? extends T>> sources, int prefetch, boolean tillTheEnd) {
@@ -1410,6 +1444,7 @@ public static <T> Flowable<T> concatDelayError(Publisher<? extends Publisher<? e
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatEager(Publisher<? extends Publisher<? extends T>> sources) {
@@ -1438,6 +1473,7 @@ public static <T> Flowable<T> concatEager(Publisher<? extends Publisher<? extend
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
@@ -1464,6 +1500,7 @@ public static <T> Flowable<T> concatEager(Publisher<? extends Publisher<? extend
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatEager(Iterable<? extends Publisher<? extends T>> sources) {
@@ -1492,6 +1529,7 @@ public static <T> Flowable<T> concatEager(Iterable<? extends Publisher<? extends
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
@@ -1545,6 +1583,7 @@ public static <T> Flowable<T> concatEager(Iterable<? extends Publisher<? extends
      * @see BackpressureStrategy
      * @see Cancellable
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> create(FlowableOnSubscribe<T> source, BackpressureStrategy mode) {
@@ -1580,6 +1619,7 @@ public static <T> Flowable<T> create(FlowableOnSubscribe<T> source, Backpressure
      *         Publisher factory function
      * @see <a href="http://reactivex.io/documentation/operators/defer.html">ReactiveX operators documentation: Defer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> defer(Callable<? extends Publisher<? extends T>> supplier) {
@@ -1605,6 +1645,7 @@ public static <T> Flowable<T> defer(Callable<? extends Publisher<? extends T>> s
      *         {@link Subscriber}'s {@link Subscriber#onComplete() onComplete} method
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Empty</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -1632,6 +1673,7 @@ public static <T> Flowable<T> empty() {
      *         the Subscriber subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> error(Callable<? extends Throwable> supplier) {
@@ -1659,6 +1701,7 @@ public static <T> Flowable<T> error(Callable<? extends Throwable> supplier) {
      *         the Subscriber subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> error(final Throwable throwable) {
@@ -1685,6 +1728,7 @@ public static <T> Flowable<T> error(final Throwable throwable) {
      * @return a Flowable that emits each item in the source Array
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> fromArray(T... items) {
@@ -1722,6 +1766,7 @@ public static <T> Flowable<T> fromArray(T... items) {
      * @see #defer(Callable)
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> fromCallable(Callable<? extends T> supplier) {
@@ -1757,6 +1802,7 @@ public static <T> Flowable<T> fromCallable(Callable<? extends T> supplier) {
      * @return a Flowable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> fromFuture(Future<? extends T> future) {
@@ -1796,6 +1842,7 @@ public static <T> Flowable<T> fromFuture(Future<? extends T> future) {
      * @return a Flowable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit) {
@@ -1839,6 +1886,7 @@ public static <T> Flowable<T> fromFuture(Future<? extends T> future, long timeou
      * @return a Flowable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Flowable<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit, Scheduler scheduler) {
@@ -1875,6 +1923,7 @@ public static <T> Flowable<T> fromFuture(Future<? extends T> future, long timeou
      * @return a Flowable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Flowable<T> fromFuture(Future<? extends T> future, Scheduler scheduler) {
@@ -1902,6 +1951,7 @@ public static <T> Flowable<T> fromFuture(Future<? extends T> future, Scheduler s
      * @return a Flowable that emits each item in the source {@link Iterable} sequence
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> fromIterable(Iterable<? extends T> source) {
@@ -1924,6 +1974,7 @@ public static <T> Flowable<T> fromIterable(Iterable<? extends T> source) {
      * @return the new Flowable instance
      * @throws NullPointerException if publisher is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -1953,6 +2004,7 @@ public static <T> Flowable<T> fromPublisher(final Publisher<? extends T> source)
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> generate(final Consumer<Emitter<T>> generator) {
@@ -1981,6 +2033,7 @@ public static <T> Flowable<T> generate(final Consumer<Emitter<T>> generator) {
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Flowable<T> generate(Callable<S> initialState, final BiConsumer<S, Emitter<T>> generator) {
@@ -2010,6 +2063,7 @@ public static <T, S> Flowable<T> generate(Callable<S> initialState, final BiCons
      * terminates the sequence or it gets cancelled
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Flowable<T> generate(Callable<S> initialState, final BiConsumer<S, Emitter<T>> generator,
@@ -2038,6 +2092,7 @@ public static <T, S> Flowable<T> generate(Callable<S> initialState, final BiCons
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Flowable<T> generate(Callable<S> initialState, BiFunction<S, Emitter<T>, S> generator) {
@@ -2066,6 +2121,7 @@ public static <T, S> Flowable<T> generate(Callable<S> initialState, BiFunction<S
      * terminates the sequence or it gets cancelled
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Flowable<T> generate(Callable<S> initialState, BiFunction<S, Emitter<T>, S> generator, Consumer<? super S> disposeState) {
@@ -2100,6 +2156,7 @@ public static <T, S> Flowable<T> generate(Callable<S> initialState, BiFunction<S
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      * @since 1.0.12
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Flowable<Long> interval(long initialDelay, long period, TimeUnit unit) {
@@ -2133,6 +2190,7 @@ public static Flowable<Long> interval(long initialDelay, long period, TimeUnit u
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      * @since 1.0.12
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Flowable<Long> interval(long initialDelay, long period, TimeUnit unit, Scheduler scheduler) {
@@ -2160,6 +2218,7 @@ public static Flowable<Long> interval(long initialDelay, long period, TimeUnit u
      * @return a Flowable that emits a sequential number each time interval
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Flowable<Long> interval(long period, TimeUnit unit) {
@@ -2189,6 +2248,7 @@ public static Flowable<Long> interval(long period, TimeUnit unit) {
      * @return a Flowable that emits a sequential number each time interval
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Flowable<Long> interval(long period, TimeUnit unit, Scheduler scheduler) {
@@ -2212,6 +2272,7 @@ public static Flowable<Long> interval(long period, TimeUnit unit, Scheduler sche
      * @param unit the unit of measure of the initialDelay and period amounts
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Flowable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit) {
@@ -2236,6 +2297,7 @@ public static Flowable<Long> intervalRange(long start, long count, long initialD
      * @param scheduler the target scheduler where the values and terminal signals will be emitted
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Flowable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit, Scheduler scheduler) {
@@ -2282,6 +2344,7 @@ public static Flowable<Long> intervalRange(long start, long count, long initialD
      * @return a Flowable that emits {@code value} as a single item and then completes
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item) {
@@ -2310,6 +2373,7 @@ public static <T> Flowable<T> just(T item) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2) {
@@ -2342,6 +2406,7 @@ public static <T> Flowable<T> just(T item1, T item2) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3) {
@@ -2377,6 +2442,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4) {
@@ -2415,6 +2481,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5) {
@@ -2456,6 +2523,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5)
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5, T item6) {
@@ -2500,6 +2568,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5,
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7) {
@@ -2547,6 +2616,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5,
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8) {
@@ -2597,6 +2667,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5,
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8, T item9) {
@@ -2650,6 +2721,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5,
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8, T item9, T item10) {
@@ -2697,6 +2769,7 @@ public static <T> Flowable<T> just(T item1, T item2, T item3, T item4, T item5,
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> sources, int maxConcurrency, int bufferSize) {
@@ -2733,6 +2806,7 @@ public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> s
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeArray(int maxConcurrency, int bufferSize, Publisher<? extends T>... sources) {
@@ -2762,6 +2836,7 @@ public static <T> Flowable<T> mergeArray(int maxConcurrency, int bufferSize, Pub
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> sources) {
@@ -2796,6 +2871,7 @@ public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> s
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> sources, int maxConcurrency) {
@@ -2826,6 +2902,7 @@ public static <T> Flowable<T> merge(Iterable<? extends Publisher<? extends T>> s
      *         {@code source} Publisher
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Publisher<? extends Publisher<? extends T>> sources) {
@@ -2862,6 +2939,7 @@ public static <T> Flowable<T> merge(Publisher<? extends Publisher<? extends T>>
      * @since 1.1.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Publisher<? extends Publisher<? extends T>> sources, int maxConcurrency) {
@@ -2890,6 +2968,7 @@ public static <T> Flowable<T> merge(Publisher<? extends Publisher<? extends T>>
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeArray(Publisher<? extends T>... sources) {
@@ -2920,6 +2999,7 @@ public static <T> Flowable<T> mergeArray(Publisher<? extends T>... sources) {
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Publisher<? extends T> source1, Publisher<? extends T> source2) {
@@ -2954,6 +3034,7 @@ public static <T> Flowable<T> merge(Publisher<? extends T> source1, Publisher<?
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Publisher<? extends T> source1, Publisher<? extends T> source2, Publisher<? extends T> source3) {
@@ -2991,6 +3072,7 @@ public static <T> Flowable<T> merge(Publisher<? extends T> source1, Publisher<?
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(
@@ -3032,6 +3114,7 @@ public static <T> Flowable<T> merge(
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? extends T>> sources) {
@@ -3072,6 +3155,7 @@ public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? ext
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? extends T>> sources, int maxConcurrency, int bufferSize) {
@@ -3111,6 +3195,7 @@ public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? ext
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, Publisher<? extends T>... sources) {
@@ -3148,6 +3233,7 @@ public static <T> Flowable<T> mergeArrayDelayError(int maxConcurrency, int buffe
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? extends T>> sources, int maxConcurrency) {
@@ -3183,6 +3269,7 @@ public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? ext
      *         {@code source} Publisher
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends Publisher<? extends T>> sources) {
@@ -3222,6 +3309,7 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends Publisher<? ex
      * @since 2.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends Publisher<? extends T>> sources, int maxConcurrency) {
@@ -3257,6 +3345,7 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends Publisher<? ex
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeArrayDelayError(Publisher<? extends T>... sources) {
@@ -3293,6 +3382,7 @@ public static <T> Flowable<T> mergeArrayDelayError(Publisher<? extends T>... sou
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends T> source1, Publisher<? extends T> source2) {
@@ -3334,6 +3424,7 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends T> source1, Pu
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends T> source1, Publisher<? extends T> source2, Publisher<? extends T> source3) {
@@ -3379,6 +3470,7 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends T> source1, Pu
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(
@@ -3409,6 +3501,7 @@ public static <T> Flowable<T> mergeDelayError(
      * @return a Flowable that never emits any items or sends any notifications to a {@link Subscriber}
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Never</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -3437,6 +3530,7 @@ public static <T> Flowable<T> never() {
      *             {@code Integer.MAX_VALUE}
      * @see <a href="http://reactivex.io/documentation/operators/range.html">ReactiveX operators documentation: Range</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Flowable<Integer> range(int start, int count) {
@@ -3476,6 +3570,7 @@ public static Flowable<Integer> range(int start, int count) {
      *             {@code Long.MAX_VALUE}
      * @see <a href="http://reactivex.io/documentation/operators/range.html">ReactiveX operators documentation: Range</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Flowable<Long> rangeLong(long start, long count) {
@@ -3521,6 +3616,7 @@ public static Flowable<Long> rangeLong(long start, long count) {
      * @return a Flowable that emits a Boolean value that indicates whether the two sequences are the same
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1, Publisher<? extends T> source2) {
@@ -3553,6 +3649,7 @@ public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1,
      *         are the same according to the specified function
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1, Publisher<? extends T> source2,
@@ -3588,6 +3685,7 @@ public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1,
      *         are the same according to the specified function
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1, Publisher<? extends T> source2,
@@ -3623,6 +3721,7 @@ public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1,
      * @return a Single that emits a Boolean value that indicates whether the two sequences are the same
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1, Publisher<? extends T> source2, int bufferSize) {
@@ -3662,6 +3761,7 @@ public static <T> Single<Boolean> sequenceEqual(Publisher<? extends T> source1,
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> switchOnNext(Publisher<? extends Publisher<? extends T>> sources, int bufferSize) {
@@ -3699,6 +3799,7 @@ public static <T> Flowable<T> switchOnNext(Publisher<? extends Publisher<? exten
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> switchOnNext(Publisher<? extends Publisher<? extends T>> sources) {
@@ -3737,6 +3838,7 @@ public static <T> Flowable<T> switchOnNext(Publisher<? extends Publisher<? exten
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> switchOnNextDelayError(Publisher<? extends Publisher<? extends T>> sources) {
@@ -3777,6 +3879,7 @@ public static <T> Flowable<T> switchOnNextDelayError(Publisher<? extends Publish
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> switchOnNextDelayError(Publisher<? extends Publisher<? extends T>> sources, int prefetch) {
@@ -3802,6 +3905,7 @@ public static <T> Flowable<T> switchOnNextDelayError(Publisher<? extends Publish
      * @return a Flowable that emits {@code 0L} after a specified delay, and then completes
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Flowable<Long> timer(long delay, TimeUnit unit) {
@@ -3831,6 +3935,7 @@ public static Flowable<Long> timer(long delay, TimeUnit unit) {
      *         completes
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Flowable<Long> timer(long delay, TimeUnit unit, Scheduler scheduler) {
@@ -3858,6 +3963,7 @@ public static Flowable<Long> timer(long delay, TimeUnit unit, Scheduler schedule
      * instances don't need conversion and is possibly a port remnant from 1.x or one should use {@link #hide()}
      * instead.
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> unsafeCreate(Publisher<T> onSubscribe) {
@@ -3891,6 +3997,7 @@ public static <T> Flowable<T> unsafeCreate(Publisher<T> onSubscribe) {
      * @return the Publisher whose lifetime controls the lifetime of the dependent resource object
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Flowable<T> using(Callable<? extends D> resourceSupplier,
@@ -3929,6 +4036,7 @@ public static <T, D> Flowable<T> using(Callable<? extends D> resourceSupplier,
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Flowable<T> using(Callable<? extends D> resourceSupplier,
@@ -3984,6 +4092,7 @@ public static <T, D> Flowable<T> using(Callable<? extends D> resourceSupplier,
      * @return a Flowable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Flowable<R> zip(Iterable<? extends Publisher<? extends T>> sources, Function<? super Object[], ? extends R> zipper) {
@@ -4036,6 +4145,7 @@ public static <T, R> Flowable<R> zip(Iterable<? extends Publisher<? extends T>>
      * @return a Flowable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Flowable<R> zip(Publisher<? extends Publisher<? extends T>> sources,
@@ -4093,6 +4203,7 @@ public static <T, R> Flowable<R> zip(Publisher<? extends Publisher<? extends T>>
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Flowable<R> zip(
@@ -4153,6 +4264,7 @@ public static <T1, T2, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Flowable<R> zip(
@@ -4215,6 +4327,7 @@ public static <T1, T2, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Flowable<R> zip(
@@ -4278,6 +4391,7 @@ public static <T1, T2, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, R> Flowable<R> zip(
@@ -4345,6 +4459,7 @@ public static <T1, T2, T3, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, R> Flowable<R> zip(
@@ -4417,6 +4532,7 @@ public static <T1, T2, T3, T4, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, R> Flowable<R> zip(
@@ -4492,6 +4608,7 @@ public static <T1, T2, T3, T4, T5, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> zip(
@@ -4571,6 +4688,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> zip(
@@ -4655,6 +4773,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> zip(
@@ -4743,6 +4862,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> zip(
@@ -4812,6 +4932,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> zip(
      * @return a Flowable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Flowable<R> zipArray(Function<? super Object[], ? extends R> zipper,
@@ -4873,6 +4994,7 @@ public static <T, R> Flowable<R> zipArray(Function<? super Object[], ? extends R
      * @return a Flowable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Flowable<R> zipIterable(Iterable<? extends Publisher<? extends T>> sources,
@@ -4907,6 +5029,7 @@ public static <T, R> Flowable<R> zipIterable(Iterable<? extends Publisher<? exte
      *         predicate; otherwise, {@code false}
      * @see <a href="http://reactivex.io/documentation/operators/all.html">ReactiveX operators documentation: All</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> all(Predicate<? super T> predicate) {
@@ -4934,6 +5057,7 @@ public final Single<Boolean> all(Predicate<? super T> predicate) {
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> ambWith(Publisher<? extends T> other) {
@@ -4964,6 +5088,7 @@ public final Flowable<T> ambWith(Publisher<? extends T> other) {
      *         Publisher satisfies the {@code predicate}
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> any(Predicate<? super T> predicate) {
@@ -4987,6 +5112,7 @@ public final Single<Boolean> any(Predicate<? super T> predicate) {
      *             if this {@code Flowable} emits no items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingFirst() {
@@ -5016,6 +5142,7 @@ public final T blockingFirst() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingFirst(T defaultItem) {
@@ -5085,6 +5212,7 @@ public final void blockingForEach(Consumer<? super T> onNext) {
      * @return an {@link Iterable} version of this {@code Flowable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingIterable() {
@@ -5108,6 +5236,7 @@ public final Iterable<T> blockingIterable() {
      * @return an {@link Iterable} version of this {@code Flowable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingIterable(int bufferSize) {
@@ -5133,6 +5262,7 @@ public final Iterable<T> blockingIterable(int bufferSize) {
      *             if this {@code Flowable} emits no items
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX documentation: Last</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingLast() {
@@ -5164,6 +5294,7 @@ public final T blockingLast() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX documentation: Last</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingLast(T defaultItem) {
@@ -5193,6 +5324,7 @@ public final T blockingLast(T defaultItem) {
      * @return an Iterable that always returns the latest item emitted by this {@code Flowable}
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingLatest() {
@@ -5219,6 +5351,7 @@ public final Iterable<T> blockingLatest() {
      *         has most recently emitted
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingMostRecent(T initialItem) {
@@ -5242,6 +5375,7 @@ public final Iterable<T> blockingMostRecent(T initialItem) {
      *         a new item, whereupon the Iterable returns that item
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingNext() {
@@ -5264,6 +5398,7 @@ public final Iterable<T> blockingNext() {
      * @return the single item emitted by this {@code Flowable}
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingSingle() {
@@ -5290,6 +5425,7 @@ public final T blockingSingle() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingSingle(T defaultItem) {
@@ -5317,6 +5453,7 @@ public final T blockingSingle(T defaultItem) {
      * @return a {@link Future} that expects a single item to be emitted by this {@code Flowable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Future<T> toFuture() {
@@ -5439,6 +5576,7 @@ public final void blockingSubscribe(Subscriber<? super T> subscriber) {
      *         {@code count} items from the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<List<T>> buffer(int count) {
@@ -5471,6 +5609,7 @@ public final Flowable<List<T>> buffer(int count) {
      *         containing at most {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<List<T>> buffer(int count, int skip) {
@@ -5507,6 +5646,7 @@ public final Flowable<List<T>> buffer(int count, int skip) {
      *         containing at most {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Flowable<U> buffer(int count, int skip, Callable<U> bufferSupplier) {
@@ -5542,6 +5682,7 @@ public final <U extends Collection<? super T>> Flowable<U> buffer(int count, int
      *         {@code count} items from the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Flowable<U> buffer(int count, Callable<U> bufferSupplier) {
@@ -5574,6 +5715,7 @@ public final <U extends Collection<? super T>> Flowable<U> buffer(int count, Cal
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<List<T>> buffer(long timespan, long timeskip, TimeUnit unit) {
@@ -5608,6 +5750,7 @@ public final Flowable<List<T>> buffer(long timespan, long timeskip, TimeUnit uni
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<List<T>> buffer(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler) {
@@ -5646,6 +5789,7 @@ public final Flowable<List<T>> buffer(long timespan, long timeskip, TimeUnit uni
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <U extends Collection<? super T>> Flowable<U> buffer(long timespan, long timeskip, TimeUnit unit,
@@ -5680,6 +5824,7 @@ public final <U extends Collection<? super T>> Flowable<U> buffer(long timespan,
      *         Publisher within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<List<T>> buffer(long timespan, TimeUnit unit) {
@@ -5714,6 +5859,7 @@ public final Flowable<List<T>> buffer(long timespan, TimeUnit unit) {
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, int count) {
@@ -5751,6 +5897,7 @@ public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, int count) {
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler scheduler, int count) {
@@ -5794,6 +5941,7 @@ public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler sc
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <U extends Collection<? super T>> Flowable<U> buffer(
@@ -5835,6 +5983,7 @@ public final <U extends Collection<? super T>> Flowable<U> buffer(
      *         Publisher within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler scheduler) {
@@ -5866,6 +6015,7 @@ public final Flowable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler sc
      *         and closed when the specified Publishers emit items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TOpening, TClosing> Flowable<List<T>> buffer(
@@ -5903,6 +6053,7 @@ public final <TOpening, TClosing> Flowable<List<T>> buffer(
      *         and closed when the specified Publishers emit items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TOpening, TClosing, U extends Collection<? super T>> Flowable<U> buffer(
@@ -5941,6 +6092,7 @@ public final <TOpening, TClosing, U extends Collection<? super T>> Flowable<U> b
      * @see #buffer(Publisher, int)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<List<T>> buffer(Publisher<B> boundaryIndicator) {
@@ -5975,6 +6127,7 @@ public final <B> Flowable<List<T>> buffer(Publisher<B> boundaryIndicator) {
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      * @see #buffer(Publisher)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<List<T>> buffer(Publisher<B> boundaryIndicator, final int initialCapacity) {
@@ -6011,6 +6164,7 @@ public final <B> Flowable<List<T>> buffer(Publisher<B> boundaryIndicator, final
      * @see #buffer(Publisher, int)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B, U extends Collection<? super T>> Flowable<U> buffer(Publisher<B> boundaryIndicator, Callable<U> bufferSupplier) {
@@ -6042,6 +6196,7 @@ public final <B, U extends Collection<? super T>> Flowable<U> buffer(Publisher<B
      *         each time the Publisher created with the {@code closingIndicator} argument emits an item
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<List<T>> buffer(Callable<? extends Publisher<B>> boundaryIndicatorSupplier) {
@@ -6076,6 +6231,7 @@ public final <B> Flowable<List<T>> buffer(Callable<? extends Publisher<B>> bound
      *         each time the Publisher created with the {@code closingIndicator} argument emits an item
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B, U extends Collection<? super T>> Flowable<U> buffer(Callable<? extends Publisher<B>> boundaryIndicatorSupplier,
@@ -6136,6 +6292,7 @@ public final <B, U extends Collection<? super T>> Flowable<U> buffer(Callable<?
      *         benefit of subsequent subscribers
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> cache() {
@@ -6197,6 +6354,7 @@ public final Flowable<T> cache() {
      *         benefit of subsequent subscribers
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> cacheWithInitialCapacity(int initialCapacity) {
@@ -6225,6 +6383,7 @@ public final Flowable<T> cacheWithInitialCapacity(int initialCapacity) {
      *         specified type
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> cast(final Class<U> clazz) {
@@ -6257,6 +6416,7 @@ public final <U> Flowable<U> cast(final Class<U> clazz) {
      *         into a single mutable data structure
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<U> collect(Callable<? extends U> initialItemSupplier, BiConsumer<? super U, ? super T> collector) {
@@ -6290,6 +6450,7 @@ public final <U> Single<U> collect(Callable<? extends U> initialItemSupplier, Bi
      *         into a single mutable data structure
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<U> collectInto(final U initialItem, BiConsumer<? super U, ? super T> collector) {
@@ -6319,6 +6480,7 @@ public final <U> Single<U> collectInto(final U initialItem, BiConsumer<? super U
      * @return the source Publisher, transformed by the transformer function
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> compose(FlowableTransformer<T, R> composer) {
@@ -6350,6 +6512,7 @@ public final <R> Flowable<R> compose(FlowableTransformer<T, R> composer) {
      *         by the source Publisher and concatenating the Publishers obtained from this transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMap(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -6383,6 +6546,7 @@ public final <R> Flowable<R> concatMap(Function<? super T, ? extends Publisher<?
      *         by the source Publisher and concatenating the Publishers obtained from this transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMap(Function<? super T, ? extends Publisher<? extends R>> mapper, int prefetch) {
@@ -6420,6 +6584,7 @@ public final <R> Flowable<R> concatMap(Function<? super T, ? extends Publisher<?
      * @param mapper the function that maps the items of this Publisher into the inner Publishers.
      * @return the new Publisher instance with the concatenation behavior
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -6452,6 +6617,7 @@ public final <R> Flowable<R> concatMapDelayError(Function<? super T, ? extends P
      *            if false, an error from the main source is signalled when the current Publisher source terminates
      * @return the new Publisher instance with the concatenation behavior
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper,
@@ -6490,6 +6656,7 @@ public final <R> Flowable<R> concatMapDelayError(Function<? super T, ? extends P
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapEager(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -6518,6 +6685,7 @@ public final <R> Flowable<R> concatMapEager(Function<? super T, ? extends Publis
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapEager(Function<? super T, ? extends Publisher<? extends R>> mapper,
@@ -6550,6 +6718,7 @@ public final <R> Flowable<R> concatMapEager(Function<? super T, ? extends Publis
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapEagerDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper,
@@ -6584,6 +6753,7 @@ public final <R> Flowable<R> concatMapEagerDelayError(Function<? super T, ? exte
      * @return the new Publisher instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> concatMapEagerDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper,
@@ -6614,6 +6784,7 @@ public final <R> Flowable<R> concatMapEagerDelayError(Function<? super T, ? exte
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> concatMapIterable(Function<? super T, ? extends Iterable<? extends U>> mapper) {
@@ -6645,6 +6816,7 @@ public final <U> Flowable<U> concatMapIterable(Function<? super T, ? extends Ite
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> concatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper, int prefetch) {
@@ -6673,6 +6845,7 @@ public final <U> Flowable<U> concatMapIterable(final Function<? super T, ? exten
      *         without interleaving them
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> concatWith(Publisher<? extends T> other) {
@@ -6699,6 +6872,7 @@ public final Flowable<T> concatWith(Publisher<? extends T> other) {
      *         or {@code false} if the source Publisher completes without emitting that item
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> contains(final Object item) {
@@ -6724,6 +6898,7 @@ public final Single<Boolean> contains(final Object item) {
      * @see <a href="http://reactivex.io/documentation/operators/count.html">ReactiveX operators documentation: Count</a>
      * @see #count()
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Long> count() {
@@ -6752,6 +6927,7 @@ public final Single<Long> count() {
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> debounce(Function<? super T, ? extends Publisher<U>> debounceIndicator) {
@@ -6794,6 +6970,7 @@ public final <U> Flowable<T> debounce(Function<? super T, ? extends Publisher<U>
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #throttleWithTimeout(long, TimeUnit)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> debounce(long timeout, TimeUnit unit) {
@@ -6838,6 +7015,7 @@ public final Flowable<T> debounce(long timeout, TimeUnit unit) {
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #throttleWithTimeout(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> debounce(long timeout, TimeUnit unit, Scheduler scheduler) {
@@ -6867,6 +7045,7 @@ public final Flowable<T> debounce(long timeout, TimeUnit unit, Scheduler schedul
      *         items, or the items emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> defaultIfEmpty(T defaultItem) {
@@ -6901,6 +7080,7 @@ public final Flowable<T> defaultIfEmpty(T defaultItem) {
      *         per-item basis
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> delay(final Function<? super T, ? extends Publisher<U>> itemDelayIndicator) {
@@ -6927,6 +7107,7 @@ public final <U> Flowable<T> delay(final Function<? super T, ? extends Publisher
      * @return the source Publisher shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> delay(long delay, TimeUnit unit) {
@@ -6955,6 +7136,7 @@ public final Flowable<T> delay(long delay, TimeUnit unit) {
      * @return the source Publisher shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> delay(long delay, TimeUnit unit, boolean delayError) {
@@ -6982,6 +7164,7 @@ public final Flowable<T> delay(long delay, TimeUnit unit, boolean delayError) {
      * @return the source Publisher shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
@@ -7012,6 +7195,7 @@ public final Flowable<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
      * @return the source Publisher shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> delay(long delay, TimeUnit unit, Scheduler scheduler, boolean delayError) {
@@ -7053,6 +7237,7 @@ public final Flowable<T> delay(long delay, TimeUnit unit, Scheduler scheduler, b
      *         Publisher on a per-item basis
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<T> delay(Publisher<U> subscriptionIndicator,
@@ -7079,6 +7264,7 @@ public final <U, V> Flowable<T> delay(Publisher<U> subscriptionIndicator,
      *         until the other Publisher emits an element or completes normally.
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> delaySubscription(Publisher<U> subscriptionIndicator) {
@@ -7104,6 +7290,7 @@ public final <U> Flowable<T> delaySubscription(Publisher<U> subscriptionIndicato
      * @return a Flowable that delays the subscription to the source Publisher by the given amount
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> delaySubscription(long delay, TimeUnit unit) {
@@ -7132,6 +7319,7 @@ public final Flowable<T> delaySubscription(long delay, TimeUnit unit) {
      *         amount, waiting and subscribing on the given Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> delaySubscription(long delay, TimeUnit unit, Scheduler scheduler) {
@@ -7157,6 +7345,7 @@ public final Flowable<T> delaySubscription(long delay, TimeUnit unit, Scheduler
      *         emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/materialize-dematerialize.html">ReactiveX operators documentation: Dematerialize</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T2> Flowable<T2> dematerialize() {
@@ -7182,6 +7371,7 @@ public final <T2> Flowable<T2> dematerialize() {
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> distinct() {
@@ -7208,6 +7398,7 @@ public final Flowable<T> distinct() {
      * @return a Flowable that emits those items emitted by the source Publisher that have distinct keys
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Flowable<T> distinct(Function<? super T, K> keySelector) {
@@ -7237,6 +7428,7 @@ public final <K> Flowable<T> distinct(Function<? super T, K> keySelector) {
      * @return a Flowable that emits those items emitted by the source Publisher that have distinct keys
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Flowable<T> distinct(Function<? super T, K> keySelector,
@@ -7263,6 +7455,7 @@ public final <K> Flowable<T> distinct(Function<? super T, K> keySelector,
      *         immediate predecessors
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> distinctUntilChanged() {
@@ -7290,6 +7483,7 @@ public final Flowable<T> distinctUntilChanged() {
      *         those of their immediate predecessors
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Flowable<T> distinctUntilChanged(Function<? super T, K> keySelector) {
@@ -7317,6 +7511,7 @@ public final <K> Flowable<T> distinctUntilChanged(Function<? super T, K> keySele
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> distinctUntilChanged(BiPredicate<? super T, ? super T> comparer) {
@@ -7345,6 +7540,7 @@ public final Flowable<T> distinctUntilChanged(BiPredicate<? super T, ? super T>
      * @return the new Flowable instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
@@ -7371,6 +7567,7 @@ public final Flowable<T> doFinally(Action onFinally) {
      * @return the new Flowable instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
@@ -7399,6 +7596,7 @@ public final Flowable<T> doAfterNext(Consumer<? super T> onAfterNext) {
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      * @see #doOnTerminate(Action)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doAfterTerminate(Action onAfterTerminate) {
@@ -7431,6 +7629,7 @@ public final Flowable<T> doAfterTerminate(Action onAfterTerminate) {
      * @return the source {@code Publisher} modified so as to call this Action when appropriate
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnCancel(Action onCancel) {
@@ -7454,6 +7653,7 @@ public final Flowable<T> doOnCancel(Action onCancel) {
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnComplete(Action onComplete) {
@@ -7477,6 +7677,7 @@ public final Flowable<T> doOnComplete(Action onComplete) {
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     private Flowable<T> doOnEach(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
@@ -7505,6 +7706,7 @@ private Flowable<T> doOnEach(Consumer<? super T> onNext, Consumer<? super Throwa
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnEach(final Consumer<? super Notification<T>> onNotification) {
@@ -7540,6 +7742,7 @@ public final Flowable<T> doOnEach(final Consumer<? super Notification<T>> onNoti
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnEach(final Subscriber<? super T> subscriber) {
@@ -7571,6 +7774,7 @@ public final Flowable<T> doOnEach(final Subscriber<? super T> subscriber) {
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnError(Consumer<? super Throwable> onError) {
@@ -7600,6 +7804,7 @@ public final Flowable<T> doOnError(Consumer<? super Throwable> onError) {
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnLifecycle(final Consumer<? super Subscription> onSubscribe,
@@ -7627,6 +7832,7 @@ public final Flowable<T> doOnLifecycle(final Consumer<? super Subscription> onSu
      * @return the source Publisher with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnNext(Consumer<? super T> onNext) {
@@ -7656,6 +7862,7 @@ public final Flowable<T> doOnNext(Consumer<? super T> onNext) {
      *      documentation: Do</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnRequest(LongConsumer onRequest) {
@@ -7682,6 +7889,7 @@ public final Flowable<T> doOnRequest(LongConsumer onRequest) {
      * @return the source {@code Publisher} modified so as to call this Consumer when appropriate
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnSubscribe(Consumer<? super Subscription> onSubscribe) {
@@ -7710,6 +7918,7 @@ public final Flowable<T> doOnSubscribe(Consumer<? super Subscription> onSubscrib
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      * @see #doAfterTerminate(Action)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> doOnTerminate(final Action onTerminate) {
@@ -7736,6 +7945,7 @@ public final Flowable<T> doOnTerminate(final Action onTerminate) {
      *         those emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> elementAt(long index) {
@@ -7768,6 +7978,7 @@ public final Maybe<T> elementAt(long index) {
      *             if {@code index} is less than 0
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> elementAt(long index, T defaultItem) {
@@ -7799,6 +8010,7 @@ public final Single<T> elementAt(long index, T defaultItem) {
      *             if {@code index} is less than 0
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> elementAtOrError(long index) {
@@ -7827,6 +8039,7 @@ public final Single<T> elementAtOrError(long index) {
      *         evaluates as {@code true}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> filter(Predicate<? super T> predicate) {
@@ -7850,6 +8063,7 @@ public final Flowable<T> filter(Predicate<? super T> predicate) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL) // take may trigger UNBOUNDED_IN
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> firstElement() {
@@ -7875,6 +8089,7 @@ public final Maybe<T> firstElement() {
      *         source Publisher completes without emitting any items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL) // take may trigger UNBOUNDED_IN
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> first(T defaultItem) {
@@ -7897,6 +8112,7 @@ public final Single<T> first(T defaultItem) {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL) // take may trigger UNBOUNDED_IN
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> firstOrError() {
@@ -7927,6 +8143,7 @@ public final Single<T> firstOrError() {
      *         transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -7960,6 +8177,7 @@ public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? e
      *         transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends R>> mapper, boolean delayErrors) {
@@ -7993,6 +8211,7 @@ public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? e
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends R>> mapper, int maxConcurrency) {
@@ -8029,6 +8248,7 @@ public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? e
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
@@ -8067,6 +8287,7 @@ public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? e
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends R>> mapper,
@@ -8113,6 +8334,7 @@ public final <R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? e
      *         specified functions to the emissions and notifications of the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(
@@ -8156,6 +8378,7 @@ public final <R> Flowable<R> flatMap(
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMap(
@@ -8197,6 +8420,7 @@ public final <R> Flowable<R> flatMap(
      *         source Publisher and the collection Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends U>> mapper,
@@ -8234,6 +8458,7 @@ public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<
      *         source Publisher and the collection Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends U>> mapper,
@@ -8274,6 +8499,7 @@ public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends U>> mapper,
@@ -8316,6 +8542,7 @@ public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> flatMap(final Function<? super T, ? extends Publisher<? extends U>> mapper,
@@ -8355,6 +8582,7 @@ public final <U, R> Flowable<R> flatMap(final Function<? super T, ? extends Publ
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<? extends U>> mapper,
@@ -8374,6 +8602,7 @@ public final <U, R> Flowable<R> flatMap(Function<? super T, ? extends Publisher<
      * @param mapper the function that received each source value and transforms them into CompletableSources.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(Function<? super T, ? extends CompletableSource> mapper) {
@@ -8397,6 +8626,7 @@ public final Completable flatMapCompletable(Function<? super T, ? extends Comple
      * @param maxConcurrency the maximum number of active subscriptions to the CompletableSources.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(Function<? super T, ? extends CompletableSource> mapper, boolean delayErrors, int maxConcurrency) {
@@ -8428,6 +8658,7 @@ public final Completable flatMapCompletable(Function<? super T, ? extends Comple
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
@@ -8459,6 +8690,7 @@ public final <U> Flowable<U> flatMapIterable(final Function<? super T, ? extends
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper, int bufferSize) {
@@ -8494,6 +8726,7 @@ public final <U> Flowable<U> flatMapIterable(final Function<? super T, ? extends
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<V> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper,
@@ -8535,6 +8768,7 @@ public final <U, V> Flowable<V> flatMapIterable(final Function<? super T, ? exte
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<V> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper,
@@ -8557,6 +8791,7 @@ public final <U, V> Flowable<V> flatMapIterable(final Function<? super T, ? exte
      * @param mapper the function that received each source value and transforms them into MaybeSources.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapMaybe(Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
@@ -8581,6 +8816,7 @@ public final <R> Flowable<R> flatMapMaybe(Function<? super T, ? extends MaybeSou
      * @param maxConcurrency the maximum number of active subscriptions to the MaybeSources.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapMaybe(Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
@@ -8602,6 +8838,7 @@ public final <R> Flowable<R> flatMapMaybe(Function<? super T, ? extends MaybeSou
      * @param mapper the function that received each source value and transforms them into SingleSources.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapSingle(Function<? super T, ? extends SingleSource<? extends R>> mapper) {
@@ -8626,6 +8863,7 @@ public final <R> Flowable<R> flatMapSingle(Function<? super T, ? extends SingleS
      * @param maxConcurrency the maximum number of active subscriptions to the SingleSources.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapSingle(Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
@@ -8654,6 +8892,7 @@ public final <R> Flowable<R> flatMapSingle(Function<? super T, ? extends SingleS
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEach(Consumer<? super T> onNext) {
@@ -8679,6 +8918,7 @@ public final Disposable forEach(Consumer<? super T> onNext) {
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(Predicate<? super T> onNext) {
@@ -8707,6 +8947,7 @@ public final Disposable forEachWhile(Predicate<? super T> onNext) {
      *             if {@code onError} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(Predicate<? super T> onNext, Consumer<? super Throwable> onError) {
@@ -8738,6 +8979,7 @@ public final Disposable forEachWhile(Predicate<? super T> onNext, Consumer<? sup
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(final Predicate<? super T> onNext, final Consumer<? super Throwable> onError,
@@ -8784,6 +9026,7 @@ public final Disposable forEachWhile(final Predicate<? super T> onNext, final Co
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Flowable<GroupedFlowable<K, T>> groupBy(Function<? super T, ? extends K> keySelector) {
@@ -8826,6 +9069,7 @@ public final <K> Flowable<GroupedFlowable<K, T>> groupBy(Function<? super T, ? e
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Flowable<GroupedFlowable<K, T>> groupBy(Function<? super T, ? extends K> keySelector, boolean delayError) {
@@ -8869,6 +9113,7 @@ public final <K> Flowable<GroupedFlowable<K, T>> groupBy(Function<? super T, ? e
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
@@ -8916,6 +9161,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T,
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
@@ -8965,6 +9211,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T,
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
@@ -9011,6 +9258,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(Function<? super T,
      *         whose durations overlap
      * @see <a href="http://reactivex.io/documentation/operators/join.html">ReactiveX operators documentation: Join</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> groupJoin(
@@ -9038,6 +9286,7 @@ public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> groupJoin(
      *
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> hide() {
@@ -9060,6 +9309,7 @@ public final Flowable<T> hide() {
      *         called by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/ignoreelements.html">ReactiveX operators documentation: IgnoreElements</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable ignoreElements() {
@@ -9084,6 +9334,7 @@ public final Completable ignoreElements() {
      * @return a Flowable that emits a Boolean
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> isEmpty() {
@@ -9124,6 +9375,7 @@ public final Single<Boolean> isEmpty() {
      *         overlapping durations
      * @see <a href="http://reactivex.io/documentation/operators/join.html">ReactiveX operators documentation: Join</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> join(
@@ -9152,6 +9404,7 @@ public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> join(
      * @return a new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> lastElement() {
@@ -9176,6 +9429,7 @@ public final Maybe<T> lastElement() {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> last(T defaultItem) {
@@ -9199,6 +9453,7 @@ public final Single<T> last(T defaultItem) {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> lastOrError() {
@@ -9235,6 +9490,7 @@ public final Single<T> lastOrError() {
      * @return a Flowable that is the result of applying the lifted Operator to the source Publisher
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> lift(FlowableOperator<? extends R, ? super T> lifter) {
@@ -9262,6 +9518,7 @@ public final <R> Flowable<R> lift(FlowableOperator<? extends R, ? super T> lifte
      *         function
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> map(Function<? super T, ? extends R> mapper) {
@@ -9286,6 +9543,7 @@ public final <R> Flowable<R> map(Function<? super T, ? extends R> mapper) {
      *         of the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/materialize-dematerialize.html">ReactiveX operators documentation: Materialize</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Notification<T>> materialize() {
@@ -9312,6 +9570,7 @@ public final Flowable<Notification<T>> materialize() {
      * @return a Flowable that emits all of the items emitted by the source Publishers
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> mergeWith(Publisher<? extends T> other) {
@@ -9348,6 +9607,7 @@ public final Flowable<T> mergeWith(Publisher<? extends T> other) {
      * @see #observeOn(Scheduler, boolean)
      * @see #observeOn(Scheduler, boolean, int)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> observeOn(Scheduler scheduler) {
@@ -9384,6 +9644,7 @@ public final Flowable<T> observeOn(Scheduler scheduler) {
      * @see #observeOn(Scheduler)
      * @see #observeOn(Scheduler, boolean, int)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> observeOn(Scheduler scheduler, boolean delayError) {
@@ -9421,6 +9682,7 @@ public final Flowable<T> observeOn(Scheduler scheduler, boolean delayError) {
      * @see #observeOn(Scheduler)
      * @see #observeOn(Scheduler, boolean)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> observeOn(Scheduler scheduler, boolean delayError, int bufferSize) {
@@ -9447,6 +9709,7 @@ public final Flowable<T> observeOn(Scheduler scheduler, boolean delayError, int
      * @return a Flowable that emits items from the source Publisher of type {@code clazz}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> ofType(final Class<U> clazz) {
@@ -9470,6 +9733,7 @@ public final <U> Flowable<U> ofType(final Class<U> clazz) {
      * @return the source Publisher modified to buffer items to the extent system resources allow
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer() {
@@ -9495,6 +9759,7 @@ public final Flowable<T> onBackpressureBuffer() {
      * @return the source Publisher modified to buffer items to the extent system resources allow
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(boolean delayError) {
@@ -9521,6 +9786,7 @@ public final Flowable<T> onBackpressureBuffer(boolean delayError) {
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(int capacity) {
@@ -9551,6 +9817,7 @@ public final Flowable<T> onBackpressureBuffer(int capacity) {
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError) {
@@ -9583,6 +9850,7 @@ public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError)
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError, boolean unbounded) {
@@ -9617,6 +9885,7 @@ public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError,
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError, boolean unbounded,
@@ -9646,6 +9915,7 @@ public final Flowable<T> onBackpressureBuffer(int capacity, boolean delayError,
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(int capacity, Action onOverflow) {
@@ -9685,6 +9955,7 @@ public final Flowable<T> onBackpressureBuffer(int capacity, Action onOverflow) {
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureBuffer(long capacity, Action onOverflow, BackpressureOverflowStrategy overflowStrategy) {
@@ -9712,6 +9983,7 @@ public final Flowable<T> onBackpressureBuffer(long capacity, Action onOverflow,
      * @return the source Publisher modified to drop {@code onNext} notifications on overflow
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureDrop() {
@@ -9739,6 +10011,7 @@ public final Flowable<T> onBackpressureDrop() {
      * @see <a href="http://reactivex.io/documentation/operators/backpressure.html">ReactiveX operators documentation: backpressure operators</a>
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureDrop(Consumer<? super T> onDrop) {
@@ -9772,6 +10045,7 @@ public final Flowable<T> onBackpressureDrop(Consumer<? super T> onDrop) {
      * @return the source Publisher modified so that it emits the most recently-received item upon request
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onBackpressureLatest() {
@@ -9813,6 +10087,7 @@ public final Flowable<T> onBackpressureLatest() {
      * @return the original Publisher, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onErrorResumeNext(Function<? super Throwable, ? extends Publisher<? extends T>> resumeFunction) {
@@ -9855,6 +10130,7 @@ public final Flowable<T> onErrorResumeNext(Function<? super Throwable, ? extends
      * @return the original Publisher, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onErrorResumeNext(final Publisher<? extends T> next) {
@@ -9893,6 +10169,7 @@ public final Flowable<T> onErrorResumeNext(final Publisher<? extends T> next) {
      * @return the original Publisher with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onErrorReturn(Function<? super Throwable, ? extends T> valueSupplier) {
@@ -9931,6 +10208,7 @@ public final Flowable<T> onErrorReturn(Function<? super Throwable, ? extends T>
      * @return the original Publisher with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onErrorReturnItem(final T item) {
@@ -9976,6 +10254,7 @@ public final Flowable<T> onErrorReturnItem(final T item) {
      * @return the original Publisher, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onExceptionResumeNext(final Publisher<? extends T> next) {
@@ -9997,6 +10276,7 @@ public final Flowable<T> onExceptionResumeNext(final Publisher<? extends T> next
      * the sequence is terminated or downstream cancels
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> onTerminateDetach() {
@@ -10022,6 +10302,7 @@ public final Flowable<T> onTerminateDetach() {
      *         to its {@link Subscriber}s
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableFlowable<T> publish() {
@@ -10053,6 +10334,7 @@ public final ConnectableFlowable<T> publish() {
      * @return a Flowable that emits the results of invoking the selector on the items emitted by a {@link ConnectableFlowable} that shares a single subscription to the underlying sequence
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> publish(Function<? super Flowable<T>, ? extends Publisher<R>> selector) {
@@ -10086,6 +10368,7 @@ public final <R> Flowable<R> publish(Function<? super Flowable<T>, ? extends Pub
      * @return a Flowable that emits the results of invoking the selector on the items emitted by a {@link ConnectableFlowable} that shares a single subscription to the underlying sequence
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> publish(Function<? super Flowable<T>, ? extends Publisher<? extends R>> selector, int prefetch) {
@@ -10115,6 +10398,7 @@ public final <R> Flowable<R> publish(Function<? super Flowable<T>, ? extends Pub
      *         to its {@link Subscriber}s
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableFlowable<T> publish(int bufferSize) {
@@ -10140,6 +10424,7 @@ public final ConnectableFlowable<T> publish(int bufferSize) {
      * @return the Publisher that rebatches request amounts from downstream
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> rebatchRequests(int n) {
@@ -10175,6 +10460,7 @@ public final Flowable<T> rebatchRequests(int n) {
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
@@ -10226,6 +10512,7 @@ public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
@@ -10276,6 +10563,7 @@ public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> reduceWith(Callable<R> seedSupplier, BiFunction<R, ? super T, R> reducer) {
@@ -10297,6 +10585,7 @@ public final <R> Single<R> reduceWith(Callable<R> seedSupplier, BiFunction<R, ?
      * @return a Flowable that emits the items emitted by the source Publisher repeatedly and in sequence
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat() {
@@ -10325,6 +10614,7 @@ public final Flowable<T> repeat() {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat(long times) {
@@ -10358,6 +10648,7 @@ public final Flowable<T> repeat(long times) {
      *             if {@code stop} is null
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatUntil(BooleanSupplier stop) {
@@ -10387,6 +10678,7 @@ public final Flowable<T> repeatUntil(BooleanSupplier stop) {
      * @return the source Publisher modified with repeat logic
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? extends Publisher<?>> handler) {
@@ -10414,6 +10706,7 @@ public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? e
      *         items to its {@link Subscriber}s
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableFlowable<T> replay() {
@@ -10443,6 +10736,7 @@ public final ConnectableFlowable<T> replay() {
      *         {@link ConnectableFlowable} that shares a single subscription to the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector) {
@@ -10477,6 +10771,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *         replaying no more than {@code bufferSize} items
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector, final int bufferSize) {
@@ -10516,6 +10811,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *         {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize, long time, TimeUnit unit) {
@@ -10558,6 +10854,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *             if {@code bufferSize} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector, final int bufferSize, final long time, final TimeUnit unit, final Scheduler scheduler) {
@@ -10596,6 +10893,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *         replaying no more than {@code bufferSize} notifications
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Flowable<R> replay(final Function<? super Flowable<T>, ? extends Publisher<R>> selector, final int bufferSize, final Scheduler scheduler) {
@@ -10633,6 +10931,7 @@ public final <R> Flowable<R> replay(final Function<? super Flowable<T>, ? extend
      *         replaying all items that were emitted within the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector, long time, TimeUnit unit) {
@@ -10670,6 +10969,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *         replaying all items that were emitted within the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publisher<R>> selector, final long time, final TimeUnit unit, final Scheduler scheduler) {
@@ -10705,6 +11005,7 @@ public final <R> Flowable<R> replay(Function<? super Flowable<T>, ? extends Publ
      *         replaying all items
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Flowable<R> replay(final Function<? super Flowable<T>, ? extends Publisher<R>> selector, final Scheduler scheduler) {
@@ -10736,6 +11037,7 @@ public final <R> Flowable<R> replay(final Function<? super Flowable<T>, ? extend
      *         replays at most {@code bufferSize} items emitted by that Publisher
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableFlowable<T> replay(final int bufferSize) {
@@ -10769,6 +11071,7 @@ public final ConnectableFlowable<T> replay(final int bufferSize) {
      *         {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final ConnectableFlowable<T> replay(int bufferSize, long time, TimeUnit unit) {
@@ -10806,6 +11109,7 @@ public final ConnectableFlowable<T> replay(int bufferSize, long time, TimeUnit u
      *             if {@code bufferSize} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableFlowable<T> replay(final int bufferSize, final long time, final TimeUnit unit, final Scheduler scheduler) {
@@ -10839,6 +11143,7 @@ public final ConnectableFlowable<T> replay(final int bufferSize, final long time
      *         replays at most {@code bufferSize} items that were emitted by the Publisher
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableFlowable<T> replay(final int bufferSize, final Scheduler scheduler) {
@@ -10870,6 +11175,7 @@ public final ConnectableFlowable<T> replay(final int bufferSize, final Scheduler
      *         replays the items that were emitted during the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final ConnectableFlowable<T> replay(long time, TimeUnit unit) {
@@ -10902,6 +11208,7 @@ public final ConnectableFlowable<T> replay(long time, TimeUnit unit) {
      *         replays the items that were emitted during the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableFlowable<T> replay(final long time, final TimeUnit unit, final Scheduler scheduler) {
@@ -10933,6 +11240,7 @@ public final ConnectableFlowable<T> replay(final long time, final TimeUnit unit,
      *         {@link Scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableFlowable<T> replay(final Scheduler scheduler) {
@@ -10964,6 +11272,7 @@ public final ConnectableFlowable<T> replay(final Scheduler scheduler) {
      * @return the source Publisher modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retry() {
@@ -10990,6 +11299,7 @@ public final Flowable<T> retry() {
      * @see #retry()
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retry(BiPredicate<? super Integer, ? super Throwable> predicate) {
@@ -11025,6 +11335,7 @@ public final Flowable<T> retry(BiPredicate<? super Integer, ? super Throwable> p
      * @return the source Publisher modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retry(long count) {
@@ -11045,6 +11356,7 @@ public final Flowable<T> retry(long count) {
      * @param predicate the predicate called with the failure Throwable and should return true to trigger a retry.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retry(long times, Predicate<? super Throwable> predicate) {
@@ -11069,6 +11381,7 @@ public final Flowable<T> retry(long times, Predicate<? super Throwable> predicat
      * @param predicate the predicate that receives the failure Throwable and should return true to trigger a retry.
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retry(Predicate<? super Throwable> predicate) {
@@ -11087,6 +11400,7 @@ public final Flowable<T> retry(Predicate<? super Throwable> predicate) {
      * @param stop the function that should return true to stop retrying
      * @return the new Flowable instance
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retryUntil(final BooleanSupplier stop) {
@@ -11145,6 +11459,7 @@ public final Flowable<T> retryUntil(final BooleanSupplier stop) {
      * @return the source Publisher modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retryWhen(
@@ -11201,6 +11516,7 @@ public final void safeSubscribe(Subscriber<? super T> s) {
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #throttleLast(long, TimeUnit)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> sample(long period, TimeUnit unit) {
@@ -11231,6 +11547,7 @@ public final Flowable<T> sample(long period, TimeUnit unit) {
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #throttleLast(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> sample(long period, TimeUnit unit, Scheduler scheduler) {
@@ -11261,6 +11578,7 @@ public final Flowable<T> sample(long period, TimeUnit unit, Scheduler scheduler)
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> sample(Publisher<U> sampler) {
@@ -11292,6 +11610,7 @@ public final <U> Flowable<T> sample(Publisher<U> sampler) {
      * @return a Flowable that emits the results of each call to the accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> scan(BiFunction<T, T, T> accumulator) {
@@ -11344,6 +11663,7 @@ public final Flowable<T> scan(BiFunction<T, T, T> accumulator) {
      *         accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> scan(final R initialValue, BiFunction<R, ? super T, R> accumulator) {
@@ -11398,6 +11718,7 @@ public final <R> Flowable<R> scan(final R initialValue, BiFunction<R, ? super T,
      *         accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> scanWith(Callable<R> seedSupplier, BiFunction<R, ? super T, R> accumulator) {
@@ -11429,6 +11750,7 @@ public final <R> Flowable<R> scanWith(Callable<R> seedSupplier, BiFunction<R, ?
      *         its Subscribers
      * @see <a href="http://reactivex.io/documentation/operators/serialize.html">ReactiveX operators documentation: Serialize</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> serialize() {
@@ -11456,6 +11778,7 @@ public final Flowable<T> serialize() {
      *         to its {@link Subscriber}s
      * @see <a href="http://reactivex.io/documentation/operators/refcount.html">ReactiveX operators documentation: RefCount</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> share() {
@@ -11479,6 +11802,7 @@ public final Flowable<T> share() {
      * @return a Maybe that emits the single item emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> singleElement() {
@@ -11505,6 +11829,7 @@ public final Maybe<T> singleElement() {
      *         the source Publisher is empty
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> single(T defaultItem) {
@@ -11530,6 +11855,7 @@ public final Single<T> single(T defaultItem) {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> singleOrError() {
@@ -11555,6 +11881,7 @@ public final Single<T> singleOrError() {
      *         {@code count} items that the source Publisher emits
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skip(long count) {
@@ -11586,6 +11913,7 @@ public final Flowable<T> skip(long count) {
      *         by {@code time} elapses and the emits the remainder
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skip(long time, TimeUnit unit) {
@@ -11615,6 +11943,7 @@ public final Flowable<T> skip(long time, TimeUnit unit) {
      *         by {@code time} and {@code scheduler} elapses, and then emits the remainder
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> skip(long time, TimeUnit unit, Scheduler scheduler) {
@@ -11646,6 +11975,7 @@ public final Flowable<T> skip(long time, TimeUnit unit, Scheduler scheduler) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skipLast(int count) {
@@ -11682,6 +12012,7 @@ public final Flowable<T> skipLast(int count) {
      *         source completes defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skipLast(long time, TimeUnit unit) {
@@ -11715,6 +12046,7 @@ public final Flowable<T> skipLast(long time, TimeUnit unit) {
      *         source completes defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skipLast(long time, TimeUnit unit, boolean delayError) {
@@ -11746,6 +12078,7 @@ public final Flowable<T> skipLast(long time, TimeUnit unit, boolean delayError)
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler) {
@@ -11780,6 +12113,7 @@ public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler)
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError) {
@@ -11816,6 +12150,7 @@ public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler,
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
@@ -11848,6 +12183,7 @@ public final Flowable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler,
      *         item, then emits the remaining items
      * @see <a href="http://reactivex.io/documentation/operators/skipuntil.html">ReactiveX operators documentation: SkipUntil</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> skipUntil(Publisher<U> other) {
@@ -11874,6 +12210,7 @@ public final <U> Flowable<T> skipUntil(Publisher<U> other) {
      *         predicate becomes false
      * @see <a href="http://reactivex.io/documentation/operators/skipwhile.html">ReactiveX operators documentation: SkipWhile</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> skipWhile(Predicate<? super T> predicate) {
@@ -11901,6 +12238,7 @@ public final Flowable<T> skipWhile(Predicate<? super T> predicate) {
      *
      * @return a Flowable that emits the items emitted by the source Publisher in sorted order
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> sorted() {
@@ -11927,6 +12265,7 @@ public final Flowable<T> sorted() {
      *            that indicates their sort order
      * @return a Flowable that emits the items emitted by the source Publisher in sorted order
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> sorted(Comparator<? super T> sortFunction) {
@@ -11954,6 +12293,7 @@ public final Flowable<T> sorted(Comparator<? super T> sortFunction) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> startWith(Iterable<? extends T> items) {
@@ -11981,6 +12321,7 @@ public final Flowable<T> startWith(Iterable<? extends T> items) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> startWith(Publisher<? extends T> other) {
@@ -12009,6 +12350,7 @@ public final Flowable<T> startWith(Publisher<? extends T> other) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> startWith(T value) {
@@ -12037,6 +12379,7 @@ public final Flowable<T> startWith(T value) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> startWithArray(T... items) {
@@ -12090,6 +12433,7 @@ public final Disposable subscribe() {
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext) {
@@ -12120,6 +12464,7 @@ public final Disposable subscribe(Consumer<? super T> onNext) {
      *             if {@code onNext} is null, or
      *             if {@code onError} is null
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError) {
@@ -12153,6 +12498,7 @@ public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super T
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
@@ -12189,6 +12535,7 @@ public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super T
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
@@ -12253,7 +12600,7 @@ public final void subscribe(Subscriber<? super T> s) {
      *
      * composite.add(source.subscribeWith(rs));
      * </code></pre>
-     * 
+     *
      * <dl>
      *  <dt><b>Backpressure:</b></dt>
      *  <dd>The backpressure behavior/expectation is determined by the supplied {@code Subscriber}.</dd>
@@ -12294,6 +12641,7 @@ public final <E extends Subscriber<? super T>> E subscribeWith(E subscriber) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #observeOn
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> subscribeOn(Scheduler scheduler) {
@@ -12322,6 +12670,7 @@ public final Flowable<T> subscribeOn(Scheduler scheduler) {
      *          alternate Publisher if the source Publisher is empty.
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> switchIfEmpty(Publisher<? extends T> other) {
@@ -12355,6 +12704,7 @@ public final Flowable<T> switchIfEmpty(Publisher<? extends T> other) {
      * @return a Flowable that emits the items emitted by the Publisher returned from applying {@code func} to the most recently emitted item emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> switchMap(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -12389,6 +12739,7 @@ public final <R> Flowable<R> switchMap(Function<? super T, ? extends Publisher<?
      * @return a Flowable that emits the items emitted by the Publisher returned from applying {@code func} to the most recently emitted item emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> switchMap(Function<? super T, ? extends Publisher<? extends R>> mapper, int bufferSize) {
@@ -12423,6 +12774,7 @@ public final <R> Flowable<R> switchMap(Function<? super T, ? extends Publisher<?
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> switchMapDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper) {
@@ -12459,6 +12811,7 @@ public final <R> Flowable<R> switchMapDelayError(Function<? super T, ? extends P
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> switchMapDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper, int bufferSize) {
@@ -12503,6 +12856,7 @@ <R> Flowable<R> switchMap0(Function<? super T, ? extends Publisher<? extends R>>
      *         all of the items from the source Publisher if that Publisher emits fewer than {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL) // may trigger UNBOUNDED_IN
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> take(long count) {
@@ -12532,6 +12886,7 @@ public final Flowable<T> take(long count) {
      * @return a Flowable that emits those items emitted by the source Publisher before the time runs out
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> take(long time, TimeUnit unit) {
@@ -12561,6 +12916,7 @@ public final Flowable<T> take(long time, TimeUnit unit) {
      *         according to the specified Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> take(long time, TimeUnit unit, Scheduler scheduler) {
@@ -12588,6 +12944,7 @@ public final Flowable<T> take(long time, TimeUnit unit, Scheduler scheduler) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> takeLast(int count) {
@@ -12627,6 +12984,7 @@ public final Flowable<T> takeLast(int count) {
      *         in a specified window of time before the Publisher completed
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> takeLast(long count, long time, TimeUnit unit) {
@@ -12662,6 +13020,7 @@ public final Flowable<T> takeLast(long count, long time, TimeUnit unit) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> takeLast(long count, long time, TimeUnit unit, Scheduler scheduler) {
@@ -12702,6 +13061,7 @@ public final Flowable<T> takeLast(long count, long time, TimeUnit unit, Schedule
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> takeLast(long count, long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
@@ -12738,6 +13098,7 @@ public final Flowable<T> takeLast(long count, long time, TimeUnit unit, Schedule
      *         time before the Publisher completed specified by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> takeLast(long time, TimeUnit unit) {
@@ -12771,6 +13132,7 @@ public final Flowable<T> takeLast(long time, TimeUnit unit) {
      *         time before the Publisher completed specified by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> takeLast(long time, TimeUnit unit, boolean delayError) {
@@ -12804,6 +13166,7 @@ public final Flowable<T> takeLast(long time, TimeUnit unit, boolean delayError)
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler) {
@@ -12840,6 +13203,7 @@ public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler)
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError) {
@@ -12878,6 +13242,7 @@ public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler,
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
@@ -12909,6 +13274,7 @@ public final Flowable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler,
      * @see Flowable#takeWhile(Predicate)
      * @since 1.1.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> takeUntil(Predicate<? super T> stopPredicate) {
@@ -12937,6 +13303,7 @@ public final Flowable<T> takeUntil(Predicate<? super T> stopPredicate) {
      * @return a Flowable that emits the items emitted by the source Publisher until such time as {@code other} emits its first item
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<T> takeUntil(Publisher<U> other) {
@@ -12964,6 +13331,7 @@ public final <U> Flowable<T> takeUntil(Publisher<U> other) {
      * @see <a href="http://reactivex.io/documentation/operators/takewhile.html">ReactiveX operators documentation: TakeWhile</a>
      * @see Flowable#takeUntil(Predicate)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> takeWhile(Predicate<? super T> predicate) {
@@ -12994,6 +13362,7 @@ public final Flowable<T> takeWhile(Predicate<? super T> predicate) {
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> throttleFirst(long windowDuration, TimeUnit unit) {
@@ -13026,6 +13395,7 @@ public final Flowable<T> throttleFirst(long windowDuration, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> throttleFirst(long skipDuration, TimeUnit unit, Scheduler scheduler) {
@@ -13059,6 +13429,7 @@ public final Flowable<T> throttleFirst(long skipDuration, TimeUnit unit, Schedul
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #sample(long, TimeUnit)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> throttleLast(long intervalDuration, TimeUnit unit) {
@@ -13093,6 +13464,7 @@ public final Flowable<T> throttleLast(long intervalDuration, TimeUnit unit) {
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #sample(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> throttleLast(long intervalDuration, TimeUnit unit, Scheduler scheduler) {
@@ -13133,6 +13505,7 @@ public final Flowable<T> throttleLast(long intervalDuration, TimeUnit unit, Sche
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #debounce(long, TimeUnit)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> throttleWithTimeout(long timeout, TimeUnit unit) {
@@ -13177,6 +13550,7 @@ public final Flowable<T> throttleWithTimeout(long timeout, TimeUnit unit) {
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>
      * @see #debounce(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> throttleWithTimeout(long timeout, TimeUnit unit, Scheduler scheduler) {
@@ -13200,6 +13574,7 @@ public final Flowable<T> throttleWithTimeout(long timeout, TimeUnit unit, Schedu
      * @return a Flowable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Timed<T>> timeInterval() {
@@ -13225,6 +13600,7 @@ public final Flowable<Timed<T>> timeInterval() {
      * @return a Flowable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Flowable<Timed<T>> timeInterval(Scheduler scheduler) {
@@ -13249,6 +13625,7 @@ public final Flowable<Timed<T>> timeInterval(Scheduler scheduler) {
      * @return a Flowable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Timed<T>> timeInterval(TimeUnit unit) {
@@ -13275,6 +13652,7 @@ public final Flowable<Timed<T>> timeInterval(TimeUnit unit) {
      * @return a Flowable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Flowable<Timed<T>> timeInterval(TimeUnit unit, Scheduler scheduler) {
@@ -13312,6 +13690,7 @@ public final Flowable<Timed<T>> timeInterval(TimeUnit unit, Scheduler scheduler)
      *         the time window defined by the selector for the previously emitted item
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <V> Flowable<T> timeout(Function<? super T, ? extends Publisher<V>> itemTimeoutIndicator) {
@@ -13349,6 +13728,7 @@ public final <V> Flowable<T> timeout(Function<? super T, ? extends Publisher<V>>
      *         by the selector for the previously emitted item
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <V> Flowable<T> timeout(Function<? super T, ? extends Publisher<V>> itemTimeoutIndicator, Flowable<? extends T> other) {
@@ -13378,6 +13758,7 @@ public final <V> Flowable<T> timeout(Function<? super T, ? extends Publisher<V>>
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> timeout(long timeout, TimeUnit timeUnit) {
@@ -13409,6 +13790,7 @@ public final Flowable<T> timeout(long timeout, TimeUnit timeUnit) {
      * @return the source Publisher modified to switch to the fallback Publisher in case of a timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Flowable<? extends T> other) {
@@ -13444,6 +13826,7 @@ public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Flowable<? ext
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler, Flowable<? extends T> other) {
@@ -13476,6 +13859,7 @@ public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler sche
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler) {
@@ -13513,6 +13897,7 @@ public final Flowable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler sche
      *         the time windows specified by the timeout selectors
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<T> timeout(Publisher<U> firstTimeoutIndicator,
@@ -13557,6 +13942,7 @@ public final <U, V> Flowable<T> timeout(Publisher<U> firstTimeoutIndicator,
      *             if {@code itemTimeoutIndicator} is null
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<T> timeout(
@@ -13600,6 +13986,7 @@ private <U, V> Flowable<T> timeout0(
      * @return a Flowable that emits timestamped items from the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Timed<T>> timestamp() {
@@ -13626,6 +14013,7 @@ public final Flowable<Timed<T>> timestamp() {
      *         the {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Flowable<Timed<T>> timestamp(Scheduler scheduler) {
@@ -13650,6 +14038,7 @@ public final Flowable<Timed<T>> timestamp(Scheduler scheduler) {
      * @return a Flowable that emits timestamped items from the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Timed<T>> timestamp(TimeUnit unit) {
@@ -13677,6 +14066,7 @@ public final Flowable<Timed<T>> timestamp(TimeUnit unit) {
      *         the {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Flowable<Timed<T>> timestamp(final TimeUnit unit, final Scheduler scheduler) {
@@ -13699,6 +14089,7 @@ public final Flowable<Timed<T>> timestamp(final TimeUnit unit, final Scheduler s
      * @param converter the function that receives the current Flowable instance and returns a value
      * @return the value returned by the function
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> R to(Function<? super Flowable<T>, R> converter) {
@@ -13736,6 +14127,7 @@ public final <R> R to(Function<? super Flowable<T>, R> converter) {
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toList() {
@@ -13770,6 +14162,7 @@ public final Single<List<T>> toList() {
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toList(final int capacityHint) {
@@ -13806,6 +14199,7 @@ public final Single<List<T>> toList(final int capacityHint) {
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Single<U> toList(Callable<U> collectionSupplier) {
@@ -13835,6 +14229,7 @@ public final <U extends Collection<? super T>> Single<U> toList(Callable<U> coll
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Single<Map<K, T>> toMap(final Function<? super T, ? extends K> keySelector) {
@@ -13868,6 +14263,7 @@ public final <K> Single<Map<K, T>> toMap(final Function<? super T, ? extends K>
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, V>> toMap(final Function<? super T, ? extends K> keySelector, final Function<? super T, ? extends V> valueSelector) {
@@ -13901,6 +14297,7 @@ public final <K, V> Single<Map<K, V>> toMap(final Function<? super T, ? extends
      *         source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, V>> toMap(final Function<? super T, ? extends K> keySelector,
@@ -13930,6 +14327,7 @@ public final <K, V> Single<Map<K, V>> toMap(final Function<? super T, ? extends
      *         the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Single<Map<K, Collection<T>>> toMultimap(Function<? super T, ? extends K> keySelector) {
@@ -13963,6 +14361,7 @@ public final <K> Single<Map<K, Collection<T>>> toMultimap(Function<? super T, ?
      *         the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector) {
@@ -13999,6 +14398,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(Function<? super T,
      *         the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
@@ -14039,6 +14439,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
@@ -14061,6 +14462,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> toObservable() {
@@ -14088,6 +14490,7 @@ public final Observable<T> toObservable() {
      *         sorted order
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList() {
@@ -14114,6 +14517,7 @@ public final Single<List<T>> toSortedList() {
      *         sorted order
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(final Comparator<? super T> comparator) {
@@ -14144,6 +14548,7 @@ public final Single<List<T>> toSortedList(final Comparator<? super T> comparator
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(final Comparator<? super T> comparator, int capacityHint) {
@@ -14176,6 +14581,7 @@ public final Single<List<T>> toSortedList(final Comparator<? super T> comparator
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(int capacityHint) {
@@ -14199,6 +14605,7 @@ public final Single<List<T>> toSortedList(int capacityHint) {
      *         {@link Scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/subscribeon.html">ReactiveX operators documentation: SubscribeOn</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<T> unsubscribeOn(Scheduler scheduler) {
@@ -14228,6 +14635,7 @@ public final Flowable<T> unsubscribeOn(Scheduler scheduler) {
      * @throws IllegalArgumentException if either count is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Flowable<T>> window(long count) {
@@ -14259,6 +14667,7 @@ public final Flowable<Flowable<T>> window(long count) {
      * @throws IllegalArgumentException if either count or skip is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Flowable<T>> window(long count, long skip) {
@@ -14292,6 +14701,7 @@ public final Flowable<Flowable<T>> window(long count, long skip) {
      * @throws IllegalArgumentException if either count or skip is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<Flowable<T>> window(long count, long skip, int bufferSize) {
@@ -14329,6 +14739,7 @@ public final Flowable<Flowable<T>> window(long count, long skip, int bufferSize)
      * @return a Flowable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit unit) {
@@ -14365,6 +14776,7 @@ public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit
      * @return a Flowable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler) {
@@ -14403,6 +14815,7 @@ public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit
      * @return a Flowable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler, int bufferSize) {
@@ -14440,6 +14853,7 @@ public final Flowable<Flowable<T>> window(long timespan, long timeskip, TimeUnit
      *         source Publisher during fixed, consecutive durations
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit) {
@@ -14476,6 +14890,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit) {
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
@@ -14515,6 +14930,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
@@ -14551,6 +14967,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
      *         source Publisher within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
@@ -14590,6 +15007,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
@@ -14631,6 +15049,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
@@ -14674,6 +15093,7 @@ public final Flowable<Flowable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Flowable<Flowable<T>> window(
@@ -14709,6 +15129,7 @@ public final Flowable<Flowable<T>> window(
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<Flowable<T>> window(Publisher<B> boundaryIndicator) {
@@ -14740,6 +15161,7 @@ public final <B> Flowable<Flowable<T>> window(Publisher<B> boundaryIndicator) {
      *         Publisher
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<Flowable<T>> window(Publisher<B> boundaryIndicator, int bufferSize) {
@@ -14775,6 +15197,7 @@ public final <B> Flowable<Flowable<T>> window(Publisher<B> boundaryIndicator, in
      *         the specified window-governing Publishers
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<Flowable<T>> window(
@@ -14813,6 +15236,7 @@ public final <U, V> Flowable<Flowable<T>> window(
      *         the specified window-governing Publishers
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Flowable<Flowable<T>> window(
@@ -14849,6 +15273,7 @@ public final <U, V> Flowable<Flowable<T>> window(
      *         whenever {@code closingSelector} emits an item
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<Flowable<T>> window(Callable<? extends Publisher<B>> boundaryIndicatorSupplier) {
@@ -14883,6 +15308,7 @@ public final <B> Flowable<Flowable<T>> window(Callable<? extends Publisher<B>> b
      *         whenever {@code closingSelector} emits an item
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Flowable<Flowable<T>> window(Callable<? extends Publisher<B>> boundaryIndicatorSupplier, int bufferSize) {
@@ -14918,6 +15344,7 @@ public final <B> Flowable<Flowable<T>> window(Callable<? extends Publisher<B>> b
      * @since 2.0
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> withLatestFrom(Publisher<? extends U> other,
@@ -14954,6 +15381,7 @@ public final <U, R> Flowable<R> withLatestFrom(Publisher<? extends U> other,
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, R> Flowable<R> withLatestFrom(Publisher<T1> source1, Publisher<T2> source2,
@@ -14990,6 +15418,7 @@ public final <T1, T2, R> Flowable<R> withLatestFrom(Publisher<T1> source1, Publi
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, T3, R> Flowable<R> withLatestFrom(
@@ -15030,6 +15459,7 @@ public final <T1, T2, T3, R> Flowable<R> withLatestFrom(
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, T3, T4, R> Flowable<R> withLatestFrom(
@@ -15063,6 +15493,7 @@ public final <T1, T2, T3, T4, R> Flowable<R> withLatestFrom(
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> withLatestFrom(Publisher<?>[] others, Function<? super Object[], R> combiner) {
@@ -15094,6 +15525,7 @@ public final <R> Flowable<R> withLatestFrom(Publisher<?>[] others, Function<? su
      * @return the new Publisher instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> withLatestFrom(Iterable<? extends Publisher<?>> others, Function<? super Object[], R> combiner) {
@@ -15132,6 +15564,7 @@ public final <R> Flowable<R> withLatestFrom(Iterable<? extends Publisher<?>> oth
      *         sequence and emits the results of {@code zipFunction} applied to these pairs
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> zipWith(Iterable<U> other,  BiFunction<? super T, ? super U, ? extends R> zipper) {
@@ -15180,6 +15613,7 @@ public final <U, R> Flowable<R> zipWith(Iterable<U> other,  BiFunction<? super T
      *         and emits the results of {@code zipFunction} applied to these pairs
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other, BiFunction<? super T, ? super U, ? extends R> zipper) {
@@ -15230,6 +15664,7 @@ public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other, BiFunction
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other,
@@ -15282,6 +15717,7 @@ public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other,
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Flowable<R> zipWith(Publisher<? extends U> other,
diff --git a/src/main/java/io/reactivex/Maybe.java b/src/main/java/io/reactivex/Maybe.java
index 99852baff6..70a0bfca8b 100644
--- a/src/main/java/io/reactivex/Maybe.java
+++ b/src/main/java/io/reactivex/Maybe.java
@@ -55,6 +55,7 @@ public abstract class Maybe<T> implements MaybeSource<T> {
      * @param sources the Iterable sequence of sources
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> amb(final Iterable<? extends MaybeSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -72,6 +73,7 @@ public static <T> Maybe<T> amb(final Iterable<? extends MaybeSource<? extends T>
      * @param sources the array of sources
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Maybe<T> ambArray(final MaybeSource<? extends T>... sources) {
@@ -98,6 +100,7 @@ public static <T> Maybe<T> ambArray(final MaybeSource<? extends T>... sources) {
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Iterable<? extends MaybeSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -124,6 +127,7 @@ public static <T> Flowable<T> concat(Iterable<? extends MaybeSource<? extends T>
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> concat(MaybeSource<? extends T> source1, MaybeSource<? extends T> source2) {
@@ -154,6 +158,7 @@ public static <T> Flowable<T> concat(MaybeSource<? extends T> source1, MaybeSour
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> concat(
@@ -188,6 +193,7 @@ public static <T> Flowable<T> concat(
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> concat(
@@ -215,6 +221,7 @@ public static <T> Flowable<T> concat(
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Publisher<? extends MaybeSource<? extends T>> sources) {
         return concat(sources, 2);
@@ -237,6 +244,7 @@ public static <T> Flowable<T> concat(Publisher<? extends MaybeSource<? extends T
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Flowable<T> concat(Publisher<? extends MaybeSource<? extends T>> sources, int prefetch) {
@@ -258,6 +266,7 @@ public static <T> Flowable<T> concat(Publisher<? extends MaybeSource<? extends T
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> concatArray(MaybeSource<? extends T>... sources) {
@@ -289,6 +298,7 @@ public static <T> Flowable<T> concatArray(MaybeSource<? extends T>... sources) {
      */
     @SuppressWarnings("unchecked")
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatArrayDelayError(MaybeSource<? extends T>... sources) {
         if (sources.length == 0) {
@@ -318,6 +328,7 @@ public static <T> Flowable<T> concatArrayDelayError(MaybeSource<? extends T>...
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatArrayEager(MaybeSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapEager((Function)MaybeToPublisher.instance());
@@ -340,6 +351,7 @@ public static <T> Flowable<T> concatArrayEager(MaybeSource<? extends T>... sourc
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatDelayError(Iterable<? extends MaybeSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -363,6 +375,7 @@ public static <T> Flowable<T> concatDelayError(Iterable<? extends MaybeSource<?
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatDelayError(Publisher<? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapDelayError((Function)MaybeToPublisher.instance());
@@ -386,6 +399,7 @@ public static <T> Flowable<T> concatDelayError(Publisher<? extends MaybeSource<?
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatEager(Iterable<? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapEager((Function)MaybeToPublisher.instance());
@@ -411,6 +425,7 @@ public static <T> Flowable<T> concatEager(Iterable<? extends MaybeSource<? exten
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concatEager(Publisher<? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapEager((Function)MaybeToPublisher.instance());
@@ -455,6 +470,7 @@ public static <T> Flowable<T> concatEager(Publisher<? extends MaybeSource<? exte
      * @see MaybeOnSubscribe
      * @see Cancellable
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> create(MaybeOnSubscribe<T> onSubscribe) {
         ObjectHelper.requireNonNull(onSubscribe, "onSubscribe is null");
@@ -473,6 +489,7 @@ public static <T> Maybe<T> create(MaybeOnSubscribe<T> onSubscribe) {
      * returns a MaybeSource instance to subscribe to
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> defer(final Callable<? extends MaybeSource<? extends T>> maybeSupplier) {
         ObjectHelper.requireNonNull(maybeSupplier, "maybeSupplier is null");
@@ -491,6 +508,7 @@ public static <T> Maybe<T> defer(final Callable<? extends MaybeSource<? extends
      * @param <T> the value type
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Maybe<T> empty() {
@@ -515,6 +533,7 @@ public static <T> Maybe<T> empty() {
      *         the subscriber subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> error(Throwable exception) {
         ObjectHelper.requireNonNull(exception, "exception is null");
@@ -539,6 +558,7 @@ public static <T> Maybe<T> error(Throwable exception) {
      *         the MaybeObserver subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> error(Callable<? extends Throwable> supplier) {
         ObjectHelper.requireNonNull(supplier, "errorSupplier is null");
@@ -557,6 +577,7 @@ public static <T> Maybe<T> error(Callable<? extends Throwable> supplier) {
      * @return the new Maybe instance
      * @throws NullPointerException if run is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromAction(final Action run) {
         ObjectHelper.requireNonNull(run, "run is null");
@@ -575,6 +596,7 @@ public static <T> Maybe<T> fromAction(final Action run) {
      * @return the new Maybe instance
      * @throws NullPointerException if completable is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromCompletable(CompletableSource completableSource) {
         ObjectHelper.requireNonNull(completableSource, "completableSource is null");
@@ -593,6 +615,7 @@ public static <T> Maybe<T> fromCompletable(CompletableSource completableSource)
      * @return the new Maybe instance
      * @throws NullPointerException if single is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromSingle(SingleSource<T> singleSource) {
         ObjectHelper.requireNonNull(singleSource, "singleSource is null");
@@ -617,6 +640,7 @@ public static <T> Maybe<T> fromSingle(SingleSource<T> singleSource) {
      *         the type of the item emitted by the {@link Maybe}.
      * @return a {@link Maybe} whose {@link MaybeObserver}s' subscriptions trigger an invocation of the given function.
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromCallable(final Callable<? extends T> callable) {
         ObjectHelper.requireNonNull(callable, "callable is null");
@@ -649,6 +673,7 @@ public static <T> Maybe<T> fromCallable(final Callable<? extends T> callable) {
      * @return a Maybe that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromFuture(Future<? extends T> future) {
         ObjectHelper.requireNonNull(future, "future is null");
@@ -685,6 +710,7 @@ public static <T> Maybe<T> fromFuture(Future<? extends T> future) {
      * @return a Maybe that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit) {
         ObjectHelper.requireNonNull(future, "future is null");
@@ -704,6 +730,7 @@ public static <T> Maybe<T> fromFuture(Future<? extends T> future, long timeout,
      * @return the new Maybe instance
      * @throws NullPointerException if run is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> fromRunnable(final Runnable run) {
         ObjectHelper.requireNonNull(run, "run is null");
@@ -730,6 +757,7 @@ public static <T> Maybe<T> fromRunnable(final Runnable run) {
      * @return a {@code Maybe} that emits {@code item}
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> just(T item) {
         ObjectHelper.requireNonNull(item, "item is null");
@@ -750,6 +778,7 @@ public static <T> Maybe<T> just(T item) {
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Iterable<? extends MaybeSource<? extends T>> sources) {
         return merge(Flowable.fromIterable(sources));
@@ -769,6 +798,7 @@ public static <T> Flowable<T> merge(Iterable<? extends MaybeSource<? extends T>>
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>> sources) {
         return merge(sources, Integer.MAX_VALUE);
@@ -789,6 +819,7 @@ public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
@@ -813,6 +844,7 @@ public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>
      *         by {@code source}
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Maybe<T> merge(MaybeSource<? extends MaybeSource<? extends T>> source) {
@@ -842,6 +874,7 @@ public static <T> Maybe<T> merge(MaybeSource<? extends MaybeSource<? extends T>>
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> merge(
@@ -877,6 +910,7 @@ public static <T> Flowable<T> merge(
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> merge(
@@ -916,6 +950,7 @@ public static <T> Flowable<T> merge(
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> merge(
@@ -943,6 +978,7 @@ public static <T> Flowable<T> merge(
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
@@ -985,6 +1021,7 @@ public static <T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeArrayDelayError(MaybeSource<? extends T>... sources) {
         return Flowable.fromArray(sources).flatMap((Function)MaybeToPublisher.instance(), true, sources.length);
@@ -1020,6 +1057,7 @@ public static <T> Flowable<T> mergeArrayDelayError(MaybeSource<? extends T>... s
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Iterable<? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).flatMap((Function)MaybeToPublisher.instance(), true);
@@ -1056,6 +1094,7 @@ public static <T> Flowable<T> mergeDelayError(Iterable<? extends MaybeSource<? e
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).flatMap((Function)MaybeToPublisher.instance(), true);
@@ -1091,6 +1130,7 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends MaybeSource<?
      */
     @SuppressWarnings({ "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(MaybeSource<? extends T> source1, MaybeSource<? extends T> source2) {
         ObjectHelper.requireNonNull(source1, "source1 is null");
@@ -1131,6 +1171,7 @@ public static <T> Flowable<T> mergeDelayError(MaybeSource<? extends T> source1,
      */
     @SuppressWarnings({ "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(MaybeSource<? extends T> source1,
             MaybeSource<? extends T> source2, MaybeSource<? extends T> source3) {
@@ -1176,6 +1217,7 @@ public static <T> Flowable<T> mergeDelayError(MaybeSource<? extends T> source1,
      */
     @SuppressWarnings({ "unchecked" })
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(
             MaybeSource<? extends T> source1, MaybeSource<? extends T> source2,
@@ -1203,6 +1245,7 @@ public static <T> Flowable<T> mergeDelayError(
      * @return a Maybe that never emits any items or sends any notifications to a {@link MaybeObserver}
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Never</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Maybe<T> never() {
@@ -1229,6 +1272,7 @@ public static <T> Maybe<T> never() {
      * @return a Single that emits a Boolean value that indicates whether the two sequences are the same
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(MaybeSource<? extends T> source1, MaybeSource<? extends T> source2) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate());
@@ -1257,6 +1301,7 @@ public static <T> Single<Boolean> sequenceEqual(MaybeSource<? extends T> source1
      *         are the same according to the specified function
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(MaybeSource<? extends T> source1, MaybeSource<? extends T> source2,
             BiPredicate<? super T, ? super T> isEqual) {
@@ -1279,6 +1324,7 @@ public static <T> Single<Boolean> sequenceEqual(MaybeSource<? extends T> source1
      * @return a Maybe that emits {@code 0L} after a specified delay
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Maybe<Long> timer(long delay, TimeUnit unit) {
         return timer(delay, unit, Schedulers.computation());
@@ -1302,6 +1348,7 @@ public static Maybe<Long> timer(long delay, TimeUnit unit) {
      * @return a Maybe that emits {@code 0L} after a specified delay, on a specified Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Maybe<Long> timer(long delay, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -1321,6 +1368,7 @@ public static Maybe<Long> timer(long delay, TimeUnit unit, Scheduler scheduler)
      * @param onSubscribe the function that is called with the subscribing MaybeObserver
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> unsafeCreate(MaybeSource<T> onSubscribe) {
         if (onSubscribe instanceof Maybe) {
@@ -1351,6 +1399,7 @@ public static <T> Maybe<T> unsafeCreate(MaybeSource<T> onSubscribe) {
      * @return the Maybe whose lifetime controls the lifetime of the dependent resource object
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Maybe<T> using(Callable<? extends D> resourceSupplier,
             Function<? super D, ? extends MaybeSource<? extends T>> sourceSupplier,
@@ -1385,6 +1434,7 @@ public static <T, D> Maybe<T> using(Callable<? extends D> resourceSupplier,
      * @return the Maybe whose lifetime controls the lifetime of the dependent resource object
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Maybe<T> using(Callable<? extends D> resourceSupplier,
             Function<? super D, ? extends MaybeSource<? extends T>> sourceSupplier,
@@ -1406,6 +1456,7 @@ public static <T, D> Maybe<T> using(Callable<? extends D> resourceSupplier,
      * @param source the source to wrap
      * @return the Maybe wrapper or the source cast to Maybe (if possible)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> wrap(MaybeSource<T> source) {
         if (source instanceof Maybe) {
@@ -1442,6 +1493,7 @@ public static <T> Maybe<T> wrap(MaybeSource<T> source) {
      * @return a Maybe that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Maybe<R> zip(Iterable<? extends MaybeSource<? extends T>> sources, Function<? super Object[], ? extends R> zipper) {
         ObjectHelper.requireNonNull(zipper, "zipper is null");
@@ -1475,6 +1527,7 @@ public static <T, R> Maybe<R> zip(Iterable<? extends MaybeSource<? extends T>> s
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2,
@@ -1513,6 +1566,7 @@ public static <T1, T2, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1555,6 +1609,7 @@ public static <T1, T2, T3, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1602,6 +1657,7 @@ public static <T1, T2, T3, T4, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1653,6 +1709,7 @@ public static <T1, T2, T3, T4, T5, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1708,6 +1765,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1768,6 +1826,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1832,6 +1891,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Maybe<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Maybe<R> zip(
             MaybeSource<? extends T1> source1, MaybeSource<? extends T2> source2, MaybeSource<? extends T3> source3,
@@ -1878,6 +1938,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Maybe<R> zip(
      * @return a Maybe that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Maybe<R> zipArray(Function<? super Object[], ? extends R> zipper,
             MaybeSource<? extends T>... sources) {
@@ -1909,6 +1970,7 @@ public static <T, R> Maybe<R> zipArray(Function<? super Object[], ? extends R> z
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> ambWith(MaybeSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -1924,6 +1986,7 @@ public final Maybe<T> ambWith(MaybeSource<? extends T> other) {
      * </dl>
      * @return the success value
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingGet() {
         BlockingMultiObserver<T> observer = new BlockingMultiObserver<T>();
@@ -1941,6 +2004,7 @@ public final T blockingGet() {
      * @param defaultValue the default item to return if this Maybe is empty
      * @return the success value
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingGet(T defaultValue) {
         ObjectHelper.requireNonNull(defaultValue, "defaultValue is null");
@@ -1968,6 +2032,7 @@ public final T blockingGet(T defaultValue) {
      *         benefit of subsequent subscribers
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> cache() {
         return RxJavaPlugins.onAssembly(new MaybeCache<T>(this));
@@ -1984,6 +2049,7 @@ public final Maybe<T> cache() {
      * @param clazz the type token to use for casting the success result from the current Maybe
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<U> cast(final Class<? extends U> clazz) {
         ObjectHelper.requireNonNull(clazz, "clazz is null");
@@ -2008,6 +2074,7 @@ public final <U> Maybe<U> cast(final Class<? extends U> clazz) {
      * @return a Maybe, transformed by the transformer function
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> compose(MaybeTransformer<T, R> transformer) {
         return wrap(transformer.apply(this));
@@ -2029,6 +2096,7 @@ public final <R> Maybe<R> compose(MaybeTransformer<T, R> transformer) {
      * @return the Maybe returned from {@code func} when applied to the item emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> concatMap(Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2055,6 +2123,7 @@ public final <R> Maybe<R> concatMap(Function<? super T, ? extends MaybeSource<?
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> concatWith(MaybeSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -2077,6 +2146,7 @@ public final Flowable<T> concatWith(MaybeSource<? extends T> other) {
      *         or {@code false} if the source Maybe completes without emitting that item
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> contains(final Object item) {
         ObjectHelper.requireNonNull(item, "item is null");
@@ -2098,6 +2168,7 @@ public final Single<Boolean> contains(final Object item) {
      * @see <a href="http://reactivex.io/documentation/operators/count.html">ReactiveX operators documentation: Count</a>
      * @see #count()
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Long> count() {
         return RxJavaPlugins.onAssembly(new MaybeCount<T>(this));
@@ -2119,6 +2190,7 @@ public final Single<Long> count() {
      *         items, or the items emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> defaultIfEmpty(T defaultItem) {
         ObjectHelper.requireNonNull(defaultItem, "item is null");
@@ -2143,6 +2215,7 @@ public final Maybe<T> defaultIfEmpty(T defaultItem) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Maybe<T> delay(long delay, TimeUnit unit) {
         return delay(delay, unit, Schedulers.computation());
@@ -2167,6 +2240,7 @@ public final Maybe<T> delay(long delay, TimeUnit unit) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -2197,6 +2271,7 @@ public final Maybe<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     public final <U, V> Maybe<T> delay(Publisher<U> delayIndicator) {
@@ -2221,6 +2296,7 @@ public final <U, V> Maybe<T> delay(Publisher<U> delayIndicator) {
      *         until the other Publisher emits an element or completes normally.
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> delaySubscription(Publisher<U> subscriptionIndicator) {
         ObjectHelper.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
@@ -2243,6 +2319,7 @@ public final <U> Maybe<T> delaySubscription(Publisher<U> subscriptionIndicator)
      * @return a Maybe that delays the subscription to the source Maybe by the given amount
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Maybe<T> delaySubscription(long delay, TimeUnit unit) {
         return delaySubscription(delay, unit, Schedulers.computation());
@@ -2268,6 +2345,7 @@ public final Maybe<T> delaySubscription(long delay, TimeUnit unit) {
      *         amount, waiting and subscribing on the given Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> delaySubscription(long delay, TimeUnit unit, Scheduler scheduler) {
         return delaySubscription(Flowable.timer(delay, unit, scheduler));
@@ -2285,6 +2363,7 @@ public final Maybe<T> delaySubscription(long delay, TimeUnit unit, Scheduler sch
      * @return the new Maybe instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Maybe<T> doAfterSuccess(Consumer<? super T> onAfterSuccess) {
@@ -2309,6 +2388,7 @@ public final Maybe<T> doAfterSuccess(Consumer<? super T> onAfterSuccess) {
      *         {@link Action}
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doAfterTerminate(Action onAfterTerminate) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2336,6 +2416,7 @@ public final Maybe<T> doAfterTerminate(Action onAfterTerminate) {
      * @return the new Maybe instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Maybe<T> doFinally(Action onFinally) {
@@ -2353,6 +2434,7 @@ public final Maybe<T> doFinally(Action onFinally) {
      * @param onDispose the runnable called when the subscription is cancelled (disposed)
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnDispose(Action onDispose) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2379,6 +2461,7 @@ public final Maybe<T> doOnDispose(Action onDispose) {
      * @return the new Maybe with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnComplete(Action onComplete) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2401,6 +2484,7 @@ public final Maybe<T> doOnComplete(Action onComplete) {
      * @param onError the consumer called with the success value of onError
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnError(Consumer<? super Throwable> onError) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2427,6 +2511,7 @@ public final Maybe<T> doOnError(Consumer<? super Throwable> onError) {
      * @param onEvent the callback to call with the terminal event tuple
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnEvent(BiConsumer<? super T, ? super Throwable> onEvent) {
         ObjectHelper.requireNonNull(onEvent, "onEvent is null");
@@ -2443,6 +2528,7 @@ public final Maybe<T> doOnEvent(BiConsumer<? super T, ? super Throwable> onEvent
      * @param onSubscribe the consumer called with the Disposable sent via onSubscribe
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnSubscribe(Consumer<? super Disposable> onSubscribe) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2465,6 +2551,7 @@ public final Maybe<T> doOnSubscribe(Consumer<? super Disposable> onSubscribe) {
      * @param onSuccess the consumer called with the success value of onSuccess
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> doOnSuccess(Consumer<? super T> onSuccess) {
         return RxJavaPlugins.onAssembly(new MaybePeek<T>(this,
@@ -2494,6 +2581,7 @@ public final Maybe<T> doOnSuccess(Consumer<? super T> onSuccess) {
      *         evaluates as {@code true}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> filter(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -2517,6 +2605,7 @@ public final Maybe<T> filter(Predicate<? super T> predicate) {
      * @return the Maybe returned from {@code func} when applied to the item emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> flatMap(Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2544,6 +2633,7 @@ public final <R> Maybe<R> flatMap(Function<? super T, ? extends MaybeSource<? ex
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> flatMap(
             Function<? super T, ? extends MaybeSource<? extends R>> onSuccessMapper,
@@ -2577,6 +2667,7 @@ public final <R> Maybe<R> flatMap(
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Maybe<R> flatMap(Function<? super T, ? extends MaybeSource<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends R> resultSelector) {
@@ -2604,6 +2695,7 @@ public final <U, R> Maybe<R> flatMap(Function<? super T, ? extends MaybeSource<?
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> flattenAsFlowable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         return RxJavaPlugins.onAssembly(new MaybeFlatMapIterableFlowable<T, U>(this, mapper));
@@ -2626,6 +2718,7 @@ public final <U> Flowable<U> flattenAsFlowable(final Function<? super T, ? exten
      * @return the new Observable instance
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> flattenAsObservable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         return RxJavaPlugins.onAssembly(new MaybeFlatMapIterableObservable<T, U>(this, mapper));
@@ -2647,6 +2740,7 @@ public final <U> Observable<U> flattenAsObservable(final Function<? super T, ? e
      * @return the Observable returned from {@code func} when applied to the item emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapObservable(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return toObservable().flatMap(mapper);
@@ -2672,6 +2766,7 @@ public final <R> Observable<R> flatMapObservable(Function<? super T, ? extends O
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapPublisher(Function<? super T, ? extends Publisher<? extends R>> mapper) {
         return toFlowable().flatMap(mapper);
@@ -2695,6 +2790,7 @@ public final <R> Flowable<R> flatMapPublisher(Function<? super T, ? extends Publ
      * @return the Single returned from {@code mapper} when applied to the item emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> flatMapSingle(final Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2720,6 +2816,7 @@ public final <R> Single<R> flatMapSingle(final Function<? super T, ? extends Sin
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0.2 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final <R> Maybe<R> flatMapSingleElement(final Function<? super T, ? extends SingleSource<? extends R>> mapper) {
@@ -2743,6 +2840,7 @@ public final <R> Maybe<R> flatMapSingleElement(final Function<? super T, ? exten
      * @return the Completable returned from {@code mapper} when applied to the item emitted by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(final Function<? super T, ? extends Completable> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2759,6 +2857,7 @@ public final Completable flatMapCompletable(final Function<? super T, ? extends
      * </dl>
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> hide() {
         return RxJavaPlugins.onAssembly(new MaybeHide<T>(this));
@@ -2777,6 +2876,7 @@ public final Maybe<T> hide() {
      *         called by the source Maybe
      * @see <a href="http://reactivex.io/documentation/operators/ignoreelements.html">ReactiveX operators documentation: IgnoreElements</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable ignoreElement() {
         return RxJavaPlugins.onAssembly(new MaybeIgnoreElementCompletable<T>(this));
@@ -2794,6 +2894,7 @@ public final Completable ignoreElement() {
      * @return a Single that emits a Boolean
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> isEmpty() {
         return RxJavaPlugins.onAssembly(new MaybeIsEmptySingle<T>(this));
@@ -2822,6 +2923,7 @@ public final Single<Boolean> isEmpty() {
      * @return a Maybe that is the result of applying the lifted Operator to the source Maybe
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> lift(final MaybeOperator<? extends R, ? super T> lift) {
         ObjectHelper.requireNonNull(lift, "onLift is null");
@@ -2844,6 +2946,7 @@ public final <R> Maybe<R> lift(final MaybeOperator<? extends R, ? super T> lift)
      * @return a Maybe that emits the item from the source Maybe, transformed by the specified function
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> map(Function<? super T, ? extends R> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2870,6 +2973,7 @@ public final <R> Maybe<R> map(Function<? super T, ? extends R> mapper) {
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> mergeWith(MaybeSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -2894,6 +2998,7 @@ public final Flowable<T> mergeWith(MaybeSource<? extends T> other) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #subscribeOn
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> observeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -2916,6 +3021,7 @@ public final Maybe<T> observeOn(final Scheduler scheduler) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<U> ofType(final Class<U> clazz) {
         ObjectHelper.requireNonNull(clazz, "clazz is null");
@@ -2935,6 +3041,7 @@ public final <U> Maybe<U> ofType(final Class<U> clazz) {
      *
      * @return the value returned by the convert function
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> R to(Function<? super Maybe<T>, R> convert) {
         try {
@@ -2958,6 +3065,7 @@ public final <R> R to(Function<? super Maybe<T>, R> convert) {
      */
     @SuppressWarnings("unchecked")
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> toFlowable() {
         if (this instanceof FuseToFlowable) {
@@ -2976,6 +3084,7 @@ public final Flowable<T> toFlowable() {
      * @return the new Observable instance
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> toObservable() {
         if (this instanceof FuseToObservable) {
@@ -2994,6 +3103,7 @@ public final Observable<T> toObservable() {
      * @param defaultValue the default item to signal in Single if this Maybe is empty
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> toSingle(T defaultValue) {
         ObjectHelper.requireNonNull(defaultValue, "defaultValue is null");
@@ -3009,6 +3119,7 @@ public final Single<T> toSingle(T defaultValue) {
      * </dl>
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> toSingle() {
         return RxJavaPlugins.onAssembly(new MaybeToSingle<T>(this, null));
@@ -3023,6 +3134,7 @@ public final Single<T> toSingle() {
      * </dl>
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorComplete() {
         return onErrorComplete(Functions.alwaysTrue());
@@ -3039,6 +3151,7 @@ public final Maybe<T> onErrorComplete() {
      * if the Throwable should be swallowed and replaced with an onComplete.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorComplete(final Predicate<? super Throwable> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -3065,6 +3178,7 @@ public final Maybe<T> onErrorComplete(final Predicate<? super Throwable> predica
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorResumeNext(final MaybeSource<? extends T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -3090,6 +3204,7 @@ public final Maybe<T> onErrorResumeNext(final MaybeSource<? extends T> next) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorResumeNext(Function<? super Throwable, ? extends MaybeSource<? extends T>> resumeFunction) {
         ObjectHelper.requireNonNull(resumeFunction, "resumeFunction is null");
@@ -3115,6 +3230,7 @@ public final Maybe<T> onErrorResumeNext(Function<? super Throwable, ? extends Ma
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorReturn(Function<? super Throwable, ? extends T> valueSupplier) {
         ObjectHelper.requireNonNull(valueSupplier, "valueSupplier is null");
@@ -3139,6 +3255,7 @@ public final Maybe<T> onErrorReturn(Function<? super Throwable, ? extends T> val
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onErrorReturnItem(final T item) {
         ObjectHelper.requireNonNull(item, "item is null");
@@ -3167,6 +3284,7 @@ public final Maybe<T> onErrorReturnItem(final T item) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onExceptionResumeNext(final MaybeSource<? extends T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -3182,6 +3300,7 @@ public final Maybe<T> onExceptionResumeNext(final MaybeSource<? extends T> next)
      * @return a Maybe which out references to the upstream producer and downstream MaybeObserver if
      * the sequence is terminated or downstream calls dispose()
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> onTerminateDetach() {
         return RxJavaPlugins.onAssembly(new MaybeDetach<T>(this));
@@ -3202,6 +3321,7 @@ public final Maybe<T> onTerminateDetach() {
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat() {
         return repeat(Long.MAX_VALUE);
@@ -3229,6 +3349,7 @@ public final Flowable<T> repeat() {
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat(long times) {
         return toFlowable().repeat(times);
@@ -3255,6 +3376,7 @@ public final Flowable<T> repeat(long times) {
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatUntil(BooleanSupplier stop) {
         return toFlowable().repeatUntil(stop);
@@ -3283,6 +3405,7 @@ public final Flowable<T> repeatUntil(BooleanSupplier stop) {
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? extends Publisher<?>> handler) {
         return toFlowable().repeatWhen(handler);
@@ -3305,6 +3428,7 @@ public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? e
      * @return the nww Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retry() {
         return retry(Long.MAX_VALUE, Functions.alwaysTrue());
@@ -3327,6 +3451,7 @@ public final Maybe<T> retry() {
      * @see #retry()
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retry(BiPredicate<? super Integer, ? super Throwable> predicate) {
         return toFlowable().retry(predicate).singleElement();
@@ -3351,6 +3476,7 @@ public final Maybe<T> retry(BiPredicate<? super Integer, ? super Throwable> pred
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retry(long count) {
         return retry(count, Functions.alwaysTrue());
@@ -3367,6 +3493,7 @@ public final Maybe<T> retry(long count) {
      * @param predicate the predicate called with the failure Throwable and should return true to trigger a retry.
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retry(long times, Predicate<? super Throwable> predicate) {
         return toFlowable().retry(times, predicate).singleElement();
@@ -3382,6 +3509,7 @@ public final Maybe<T> retry(long times, Predicate<? super Throwable> predicate)
      * @param predicate the predicate that receives the failure Throwable and should return true to trigger a retry.
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retry(Predicate<? super Throwable> predicate) {
         return retry(Long.MAX_VALUE, predicate);
@@ -3396,6 +3524,7 @@ public final Maybe<T> retry(Predicate<? super Throwable> predicate) {
      * @param stop the function that should return true to stop retrying
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retryUntil(final BooleanSupplier stop) {
         ObjectHelper.requireNonNull(stop, "stop is null");
@@ -3450,6 +3579,7 @@ public final Maybe<T> retryUntil(final BooleanSupplier stop) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> retryWhen(
             final Function<? super Flowable<Throwable>, ? extends Publisher<?>> handler) {
@@ -3491,6 +3621,7 @@ public final Disposable subscribe() {
      *             if {@code onSuccess} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onSuccess) {
         return subscribe(onSuccess, Functions.ERROR_CONSUMER, Functions.EMPTY_ACTION);
@@ -3516,6 +3647,7 @@ public final Disposable subscribe(Consumer<? super T> onSuccess) {
      *             if {@code onSuccess} is null, or
      *             if {@code onError} is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onSuccess, Consumer<? super Throwable> onError) {
         return subscribe(onSuccess, onError, Functions.EMPTY_ACTION);
@@ -3545,14 +3677,13 @@ public final Disposable subscribe(Consumer<? super T> onSuccess, Consumer<? supe
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onSuccess, Consumer<? super Throwable> onError,
             Action onComplete) {
         return subscribeWith(new MaybeCallbackObserver<T>(onSuccess, onError, onComplete));
     }
 
-
-
     @SchedulerSupport(SchedulerSupport.NONE)
     @Override
     public final void subscribe(MaybeObserver<? super T> observer) {
@@ -3596,6 +3727,7 @@ public final void subscribe(MaybeObserver<? super T> observer) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #observeOn
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> subscribeOn(Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -3646,6 +3778,7 @@ public final <E extends MaybeObserver<? super T>> E subscribeWith(E observer) {
      * @return  a Maybe that emits the items emitted by the source Maybe or the items of an
      *          alternate MaybeSource if the source Maybe is empty.
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> switchIfEmpty(MaybeSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -3670,6 +3803,7 @@ public final Maybe<T> switchIfEmpty(MaybeSource<? extends T> other) {
      * @return a Maybe that emits the items emitted by the source Maybe until such time as {@code other} emits its first item
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> takeUntil(MaybeSource<U> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -3698,6 +3832,7 @@ public final <U> Maybe<T> takeUntil(MaybeSource<U> other) {
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> takeUntil(Publisher<U> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -3722,6 +3857,7 @@ public final <U> Maybe<T> takeUntil(Publisher<U> other) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Maybe<T> timeout(long timeout, TimeUnit timeUnit) {
         return timeout(timeout, timeUnit, Schedulers.computation());
@@ -3747,6 +3883,7 @@ public final Maybe<T> timeout(long timeout, TimeUnit timeUnit) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, MaybeSource<? extends T> fallback) {
         ObjectHelper.requireNonNull(fallback, "other is null");
@@ -3775,6 +3912,7 @@ public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, MaybeSource<? ext
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler, MaybeSource<? extends T> fallback) {
         ObjectHelper.requireNonNull(fallback, "fallback is null");
@@ -3802,6 +3940,7 @@ public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, Scheduler schedul
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler) {
         return timeout(timer(timeout, timeUnit, scheduler));
@@ -3819,6 +3958,7 @@ public final Maybe<T> timeout(long timeout, TimeUnit timeUnit, Scheduler schedul
      * or onComplete.
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> timeout(MaybeSource<U> timeoutIndicator) {
         ObjectHelper.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
@@ -3839,6 +3979,7 @@ public final <U> Maybe<T> timeout(MaybeSource<U> timeoutIndicator) {
      * @param fallback the MaybeSource that is subscribed to if the current Maybe times out
      * @return the new Maybe instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> timeout(MaybeSource<U> timeoutIndicator, MaybeSource<? extends T> fallback) {
         ObjectHelper.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
@@ -3862,6 +4003,7 @@ public final <U> Maybe<T> timeout(MaybeSource<U> timeoutIndicator, MaybeSource<?
      * @return the new Maybe instance
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> timeout(Publisher<U> timeoutIndicator) {
         ObjectHelper.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
@@ -3886,6 +4028,7 @@ public final <U> Maybe<T> timeout(Publisher<U> timeoutIndicator) {
      * @return the new Maybe instance
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Maybe<T> timeout(Publisher<U> timeoutIndicator, MaybeSource<? extends T> fallback) {
         ObjectHelper.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
@@ -3904,6 +4047,7 @@ public final <U> Maybe<T> timeout(Publisher<U> timeoutIndicator, MaybeSource<? e
      * @return the new Maybe instance
      * @throws NullPointerException if scheduler is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Maybe<T> unsubscribeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -3915,10 +4059,10 @@ public final Maybe<T> unsubscribeOn(final Scheduler scheduler) {
      * to those values and emits the BiFunction's resulting value to downstream.
      *
      * <img width="640" height="380" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/zip.png" alt="">
-     * 
+     *
      * <p>If either this or the other MaybeSource is empty or signals an error, the resulting Maybe will
      * terminate immediately and dispose the other source.
-     * 
+     *
      * <dl>
      *  <dt><b>Scheduler:</b></dt>
      *  <dd>{@code zipWith} does not operate by default on a particular {@link Scheduler}.</dd>
@@ -3936,6 +4080,7 @@ public final Maybe<T> unsubscribeOn(final Scheduler scheduler) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Maybe<R> zipWith(MaybeSource<? extends U> other, BiFunction<? super T, ? super U, ? extends R> zipper) {
         ObjectHelper.requireNonNull(other, "other is null");
diff --git a/src/main/java/io/reactivex/Observable.java b/src/main/java/io/reactivex/Observable.java
index 13138e6a35..08b9e40e61 100644
--- a/src/main/java/io/reactivex/Observable.java
+++ b/src/main/java/io/reactivex/Observable.java
@@ -74,6 +74,7 @@ public abstract class Observable<T> implements ObservableSource<T> {
      *         emitted an item or sent a termination notification
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> amb(Iterable<? extends ObservableSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -98,6 +99,7 @@ public static <T> Observable<T> amb(Iterable<? extends ObservableSource<? extend
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> ambArray(ObservableSource<? extends T>... sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -151,6 +153,7 @@ public static int bufferSize() {
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatest(Function<? super Object[], ? extends R> combiner, int bufferSize, ObservableSource<? extends T>... sources) {
         return combineLatest(sources, combiner, bufferSize);
@@ -183,6 +186,7 @@ public static <T, R> Observable<R> combineLatest(Function<? super Object[], ? ex
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatest(Iterable<? extends ObservableSource<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -219,6 +223,7 @@ public static <T, R> Observable<R> combineLatest(Iterable<? extends ObservableSo
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatest(Iterable<? extends ObservableSource<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -258,6 +263,7 @@ public static <T, R> Observable<R> combineLatest(Iterable<? extends ObservableSo
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatest(ObservableSource<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -293,6 +299,7 @@ public static <T, R> Observable<R> combineLatest(ObservableSource<? extends T>[]
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatest(ObservableSource<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -333,6 +340,7 @@ public static <T, R> Observable<R> combineLatest(ObservableSource<? extends T>[]
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -368,6 +376,7 @@ public static <T1, T2, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -407,6 +416,7 @@ public static <T1, T2, T3, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -449,6 +459,7 @@ public static <T1, T2, T3, T4, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -495,6 +506,7 @@ public static <T1, T2, T3, T4, T5, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -544,6 +556,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -597,6 +610,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -653,6 +667,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> combineLatest(
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> combineLatest(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -690,6 +705,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> combineLates
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatestDelayError(ObservableSource<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -725,6 +741,7 @@ public static <T, R> Observable<R> combineLatestDelayError(ObservableSource<? ex
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatestDelayError(Function<? super Object[], ? extends R> combiner,
             int bufferSize, ObservableSource<? extends T>... sources) {
@@ -761,6 +778,7 @@ public static <T, R> Observable<R> combineLatestDelayError(Function<? super Obje
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatestDelayError(ObservableSource<? extends T>[] sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -802,6 +820,7 @@ public static <T, R> Observable<R> combineLatestDelayError(ObservableSource<? ex
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatestDelayError(Iterable<? extends ObservableSource<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner) {
@@ -838,6 +857,7 @@ public static <T, R> Observable<R> combineLatestDelayError(Iterable<? extends Ob
      *         ObservableSources by means of the given aggregation function
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> combineLatestDelayError(Iterable<? extends ObservableSource<? extends T>> sources,
             Function<? super Object[], ? extends R> combiner, int bufferSize) {
@@ -864,6 +884,7 @@ public static <T, R> Observable<R> combineLatestDelayError(Iterable<? extends Ob
      * @return the new Observable instance
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(Iterable<? extends ObservableSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -887,6 +908,7 @@ public static <T> Observable<T> concat(Iterable<? extends ObservableSource<? ext
      *         {@code ObservableSources}, one after the other, without interleaving them
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concat(sources, bufferSize());
@@ -912,6 +934,7 @@ public static <T> Observable<T> concat(ObservableSource<? extends ObservableSour
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(ObservableSource<? extends ObservableSource<? extends T>> sources, int prefetch) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -938,6 +961,7 @@ public static <T> Observable<T> concat(ObservableSource<? extends ObservableSour
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
         return concatArray(source1, source2);
@@ -965,6 +989,7 @@ public static <T> Observable<T> concat(ObservableSource<? extends T> source1, Ob
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(
             ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
@@ -996,6 +1021,7 @@ public static <T> Observable<T> concat(
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concat(
             ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
@@ -1019,6 +1045,7 @@ public static <T> Observable<T> concat(
      * @throws NullPointerException if sources is null
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatArray(ObservableSource<? extends T>... sources) {
         if (sources.length == 0) {
@@ -1045,6 +1072,7 @@ public static <T> Observable<T> concatArray(ObservableSource<? extends T>... sou
      * @throws NullPointerException if sources is null
      */
     @SuppressWarnings({ "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatArrayDelayError(ObservableSource<? extends T>... sources) {
         if (sources.length == 0) {
@@ -1073,6 +1101,7 @@ public static <T> Observable<T> concatArrayDelayError(ObservableSource<? extends
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatArrayEager(ObservableSource<? extends T>... sources) {
         return concatArrayEager(bufferSize(), bufferSize(), sources);
@@ -1097,6 +1126,7 @@ public static <T> Observable<T> concatArrayEager(ObservableSource<? extends T>..
      * @since 2.0
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatArrayEager(int maxConcurrency, int prefetch, ObservableSource<? extends T>... sources) {
         return fromArray(sources).concatMapEagerDelayError((Function)Functions.identity(), maxConcurrency, prefetch, false);
@@ -1116,6 +1146,7 @@ public static <T> Observable<T> concatArrayEager(int maxConcurrency, int prefetc
      * @param sources the Iterable sequence of ObservableSources
      * @return the new ObservableSource with the concatenating behavior
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatDelayError(Iterable<? extends ObservableSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -1136,6 +1167,7 @@ public static <T> Observable<T> concatDelayError(Iterable<? extends ObservableSo
      * @param sources the ObservableSource sequence of ObservableSources
      * @return the new ObservableSource with the concatenating behavior
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concatDelayError(sources, bufferSize(), true);
@@ -1159,6 +1191,7 @@ public static <T> Observable<T> concatDelayError(ObservableSource<? extends Obse
      * @return the new ObservableSource with the concatenating behavior
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources, int prefetch, boolean tillTheEnd) {
         return RxJavaPlugins.onAssembly(new ObservableConcatMap(sources, Functions.identity(), prefetch, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY));
@@ -1181,6 +1214,7 @@ public static <T> Observable<T> concatDelayError(ObservableSource<? extends Obse
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatEager(ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
@@ -1207,6 +1241,7 @@ public static <T> Observable<T> concatEager(ObservableSource<? extends Observabl
      * @since 2.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatEager(ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int prefetch) {
         return wrap(sources).concatMapEager((Function)Functions.identity(), maxConcurrency, prefetch);
@@ -1229,6 +1264,7 @@ public static <T> Observable<T> concatEager(ObservableSource<? extends Observabl
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatEager(Iterable<? extends ObservableSource<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
@@ -1255,6 +1291,7 @@ public static <T> Observable<T> concatEager(Iterable<? extends ObservableSource<
      * @since 2.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> concatEager(Iterable<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int prefetch) {
         return fromIterable(sources).concatMapEagerDelayError((Function)Functions.identity(), maxConcurrency, prefetch, false);
@@ -1304,6 +1341,7 @@ public static <T> Observable<T> concatEager(Iterable<? extends ObservableSource<
      * @see ObservableEmitter
      * @see Cancellable
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> create(ObservableOnSubscribe<T> source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -1334,6 +1372,7 @@ public static <T> Observable<T> create(ObservableOnSubscribe<T> source) {
      *         ObservableSource factory function
      * @see <a href="http://reactivex.io/documentation/operators/defer.html">ReactiveX operators documentation: Defer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> defer(Callable<? extends ObservableSource<? extends T>> supplier) {
         ObjectHelper.requireNonNull(supplier, "supplier is null");
@@ -1356,6 +1395,7 @@ public static <T> Observable<T> defer(Callable<? extends ObservableSource<? exte
      *         {@link Observer}'s {@link Observer#onComplete() onComplete} method
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Empty</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Observable<T> empty() {
@@ -1380,6 +1420,7 @@ public static <T> Observable<T> empty() {
      *         the Observer subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> error(Callable<? extends Throwable> errorSupplier) {
         ObjectHelper.requireNonNull(errorSupplier, "errorSupplier is null");
@@ -1404,6 +1445,7 @@ public static <T> Observable<T> error(Callable<? extends Throwable> errorSupplie
      *         the Observer subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> error(final Throwable exception) {
         ObjectHelper.requireNonNull(exception, "e is null");
@@ -1426,6 +1468,7 @@ public static <T> Observable<T> error(final Throwable exception) {
      * @return an Observable that emits each item in the source Array
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromArray(T... items) {
         ObjectHelper.requireNonNull(items, "items is null");
@@ -1460,6 +1503,7 @@ public static <T> Observable<T> fromArray(T... items) {
      * @see #defer(Callable)
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromCallable(Callable<? extends T> supplier) {
         ObjectHelper.requireNonNull(supplier, "supplier is null");
@@ -1492,6 +1536,7 @@ public static <T> Observable<T> fromCallable(Callable<? extends T> supplier) {
      * @return an Observable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromFuture(Future<? extends T> future) {
         ObjectHelper.requireNonNull(future, "future is null");
@@ -1528,6 +1573,7 @@ public static <T> Observable<T> fromFuture(Future<? extends T> future) {
      * @return an Observable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit) {
         ObjectHelper.requireNonNull(future, "future is null");
@@ -1568,6 +1614,7 @@ public static <T> Observable<T> fromFuture(Future<? extends T> future, long time
      * @return an Observable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Observable<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -1602,6 +1649,7 @@ public static <T> Observable<T> fromFuture(Future<? extends T> future, long time
      * @return an Observable that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Observable<T> fromFuture(Future<? extends T> future, Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -1626,6 +1674,7 @@ public static <T> Observable<T> fromFuture(Future<? extends T> future, Scheduler
      * @return an Observable that emits each item in the source {@link Iterable} sequence
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromIterable(Iterable<? extends T> source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -1647,6 +1696,7 @@ public static <T> Observable<T> fromIterable(Iterable<? extends T> source) {
      * @throws NullPointerException if publisher is null
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> fromPublisher(Publisher<? extends T> publisher) {
         ObjectHelper.requireNonNull(publisher, "publisher is null");
@@ -1669,6 +1719,7 @@ public static <T> Observable<T> fromPublisher(Publisher<? extends T> publisher)
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> generate(final Consumer<Emitter<T>> generator) {
         ObjectHelper.requireNonNull(generator, "generator  is null");
@@ -1694,6 +1745,7 @@ public static <T> Observable<T> generate(final Consumer<Emitter<T>> generator) {
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Observable<T> generate(Callable<S> initialState, final BiConsumer<S, Emitter<T>> generator) {
         ObjectHelper.requireNonNull(generator, "generator  is null");
@@ -1720,6 +1772,7 @@ public static <T, S> Observable<T> generate(Callable<S> initialState, final BiCo
      * terminates the sequence or it gets cancelled
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Observable<T> generate(
             final Callable<S> initialState,
@@ -1748,6 +1801,7 @@ public static <T, S> Observable<T> generate(
      * in a call will make the operator signal {@code IllegalStateException}.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Observable<T> generate(Callable<S> initialState, BiFunction<S, Emitter<T>, S> generator) {
         return generate(initialState, generator, Functions.emptyConsumer());
@@ -1774,6 +1828,7 @@ public static <T, S> Observable<T> generate(Callable<S> initialState, BiFunction
      * terminates the sequence or it gets cancelled
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, S> Observable<T> generate(Callable<S> initialState, BiFunction<S, Emitter<T>, S> generator,
             Consumer<? super S> disposeState) {
@@ -1804,6 +1859,7 @@ public static <T, S> Observable<T> generate(Callable<S> initialState, BiFunction
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      * @since 1.0.12
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Observable<Long> interval(long initialDelay, long period, TimeUnit unit) {
         return interval(initialDelay, period, unit, Schedulers.computation());
@@ -1832,6 +1888,7 @@ public static Observable<Long> interval(long initialDelay, long period, TimeUnit
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      * @since 1.0.12
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Observable<Long> interval(long initialDelay, long period, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -1856,6 +1913,7 @@ public static Observable<Long> interval(long initialDelay, long period, TimeUnit
      * @return an Observable that emits a sequential number each time interval
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Observable<Long> interval(long period, TimeUnit unit) {
         return interval(period, period, unit, Schedulers.computation());
@@ -1880,6 +1938,7 @@ public static Observable<Long> interval(long period, TimeUnit unit) {
      * @return an Observable that emits a sequential number each time interval
      * @see <a href="http://reactivex.io/documentation/operators/interval.html">ReactiveX operators documentation: Interval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Observable<Long> interval(long period, TimeUnit unit, Scheduler scheduler) {
         return interval(period, period, unit, scheduler);
@@ -1902,6 +1961,7 @@ public static Observable<Long> interval(long period, TimeUnit unit, Scheduler sc
      * @param unit the unit of measure of the initialDelay and period amounts
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Observable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit) {
         return intervalRange(start, count, initialDelay, period, unit, Schedulers.computation());
@@ -1924,6 +1984,7 @@ public static Observable<Long> intervalRange(long start, long count, long initia
      * @param scheduler the target scheduler where the values and terminal signals will be emitted
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Observable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit, Scheduler scheduler) {
         if (count < 0) {
@@ -1968,6 +2029,7 @@ public static Observable<Long> intervalRange(long start, long count, long initia
      * @return an Observable that emits {@code value} as a single item and then completes
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item) {
         ObjectHelper.requireNonNull(item, "The item is null");
@@ -1993,6 +2055,7 @@ public static <T> Observable<T> just(T item) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2022,6 +2085,7 @@ public static <T> Observable<T> just(T item1, T item2) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2054,6 +2118,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2089,6 +2154,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4) {
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2127,6 +2193,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5, T item6) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2168,6 +2235,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2212,6 +2280,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2259,6 +2328,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8, T item9) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2309,6 +2379,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5, T item6, T item7, T item8, T item9, T item10) {
         ObjectHelper.requireNonNull(item1, "The first item is null");
@@ -2352,6 +2423,7 @@ public static <T> Observable<T> just(T item1, T item2, T item3, T item4, T item5
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
@@ -2384,6 +2456,7 @@ public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? exte
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeArray(int maxConcurrency, int bufferSize, ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
@@ -2409,6 +2482,7 @@ public static <T> Observable<T> mergeArray(int maxConcurrency, int bufferSize, O
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity());
@@ -2439,6 +2513,7 @@ public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? exte
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), maxConcurrency);
@@ -2464,6 +2539,7 @@ public static <T> Observable<T> merge(Iterable<? extends ObservableSource<? exte
      *         {@code source} ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Observable<T> merge(ObservableSource<? extends ObservableSource<? extends T>> sources) {
@@ -2497,6 +2573,7 @@ public static <T> Observable<T> merge(ObservableSource<? extends ObservableSourc
      * @since 1.1.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), false, maxConcurrency, bufferSize()));
@@ -2523,6 +2600,7 @@ public static <T> Observable<T> merge(ObservableSource<? extends ObservableSourc
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
         ObjectHelper.requireNonNull(source1, "source1 is null");
@@ -2553,6 +2631,7 @@ public static <T> Observable<T> merge(ObservableSource<? extends T> source1, Obs
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2, ObservableSource<? extends T> source3) {
         ObjectHelper.requireNonNull(source1, "source1 is null");
@@ -2586,6 +2665,7 @@ public static <T> Observable<T> merge(ObservableSource<? extends T> source1, Obs
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> merge(
             ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
@@ -2616,6 +2696,7 @@ public static <T> Observable<T> merge(
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeArray(ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), sources.length);
@@ -2647,6 +2728,7 @@ public static <T> Observable<T> mergeArray(ObservableSource<? extends T>... sour
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSource<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true);
@@ -2682,6 +2764,7 @@ public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSou
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
@@ -2717,6 +2800,7 @@ public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSou
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
@@ -2750,6 +2834,7 @@ public static <T> Observable<T> mergeArrayDelayError(int maxConcurrency, int buf
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency);
@@ -2780,6 +2865,7 @@ public static <T> Observable<T> mergeDelayError(Iterable<? extends ObservableSou
      *         {@code source} ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Observable<T> mergeDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources) {
@@ -2816,6 +2902,7 @@ public static <T> Observable<T> mergeDelayError(ObservableSource<? extends Obser
      * @since 2.0
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), true, maxConcurrency, bufferSize()));
@@ -2848,6 +2935,7 @@ public static <T> Observable<T> mergeDelayError(ObservableSource<? extends Obser
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
         ObjectHelper.requireNonNull(source1, "source1 is null");
@@ -2885,6 +2973,7 @@ public static <T> Observable<T> mergeDelayError(ObservableSource<? extends T> so
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2, ObservableSource<? extends T> source3) {
         ObjectHelper.requireNonNull(source1, "source1 is null");
@@ -2925,6 +3014,7 @@ public static <T> Observable<T> mergeDelayError(ObservableSource<? extends T> so
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeDelayError(
             ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
@@ -2962,6 +3052,7 @@ public static <T> Observable<T> mergeDelayError(
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> mergeArrayDelayError(ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, sources.length);
@@ -2983,6 +3074,7 @@ public static <T> Observable<T> mergeArrayDelayError(ObservableSource<? extends
      * @return an Observable that never emits any items or sends any notifications to an {@link Observer}
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Never</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Observable<T> never() {
@@ -3008,6 +3100,7 @@ public static <T> Observable<T> never() {
      *             {@code Integer.MAX_VALUE}
      * @see <a href="http://reactivex.io/documentation/operators/range.html">ReactiveX operators documentation: Range</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Observable<Integer> range(final int start, final int count) {
         if (count < 0) {
@@ -3044,6 +3137,7 @@ public static Observable<Integer> range(final int start, final int count) {
      *             {@code Long.MAX_VALUE}
      * @see <a href="http://reactivex.io/documentation/operators/range.html">ReactiveX operators documentation: Range</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static Observable<Long> rangeLong(long start, long count) {
         if (count < 0) {
@@ -3085,6 +3179,7 @@ public static Observable<Long> rangeLong(long start, long count) {
      * @return a Single that emits a Boolean value that indicates whether the two sequences are the same
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate(), bufferSize());
@@ -3113,6 +3208,7 @@ public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> so
      *         are the same according to the specified function
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
             BiPredicate<? super T, ? super T> isEqual) {
@@ -3144,6 +3240,7 @@ public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> so
      *         are the same according to the specified function
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
             BiPredicate<? super T, ? super T> isEqual, int bufferSize) {
@@ -3175,6 +3272,7 @@ public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> so
      * @return a Single that emits a Boolean value that indicates whether the two sequences are the same
      * @see <a href="http://reactivex.io/documentation/operators/sequenceequal.html">ReactiveX operators documentation: SequenceEqual</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> source1, ObservableSource<? extends T> source2,
             int bufferSize) {
@@ -3209,6 +3307,7 @@ public static <T> Single<Boolean> sequenceEqual(ObservableSource<? extends T> so
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> switchOnNext(ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -3240,6 +3339,7 @@ public static <T> Observable<T> switchOnNext(ObservableSource<? extends Observab
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> switchOnNext(ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return switchOnNext(sources, bufferSize());
@@ -3272,6 +3372,7 @@ public static <T> Observable<T> switchOnNext(ObservableSource<? extends Observab
      * @see <a href="http://reactivex.io/documentation/operators/switch.html">ReactiveX operators documentation: Switch</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> switchOnNextDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return switchOnNextDelayError(sources, bufferSize());
@@ -3307,6 +3408,7 @@ public static <T> Observable<T> switchOnNextDelayError(ObservableSource<? extend
      * @since 2.0
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> switchOnNextDelayError(ObservableSource<? extends ObservableSource<? extends T>> sources, int prefetch) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -3330,6 +3432,7 @@ public static <T> Observable<T> switchOnNextDelayError(ObservableSource<? extend
      * @return an Observable that {@code 0L} after a specified delay, and then completes
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Observable<Long> timer(long delay, TimeUnit unit) {
         return timer(delay, unit, Schedulers.computation());
@@ -3355,6 +3458,7 @@ public static Observable<Long> timer(long delay, TimeUnit unit) {
      *         completes
      * @see <a href="http://reactivex.io/documentation/operators/timer.html">ReactiveX operators documentation: Timer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Observable<Long> timer(long delay, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -3375,6 +3479,7 @@ public static Observable<Long> timer(long delay, TimeUnit unit, Scheduler schedu
      * @param onSubscribe the ObservableSource instance to wrap
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> unsafeCreate(ObservableSource<T> onSubscribe) {
         ObjectHelper.requireNonNull(onSubscribe, "source is null");
@@ -3406,6 +3511,7 @@ public static <T> Observable<T> unsafeCreate(ObservableSource<T> onSubscribe) {
      * @return the ObservableSource whose lifetime controls the lifetime of the dependent resource object
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Observable<T> using(Callable<? extends D> resourceSupplier, Function<? super D, ? extends ObservableSource<? extends T>> sourceSupplier, Consumer<? super D> disposer) {
         return using(resourceSupplier, sourceSupplier, disposer, true);
@@ -3439,6 +3545,7 @@ public static <T, D> Observable<T> using(Callable<? extends D> resourceSupplier,
      * @see <a href="http://reactivex.io/documentation/operators/using.html">ReactiveX operators documentation: Using</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, D> Observable<T> using(Callable<? extends D> resourceSupplier, Function<? super D, ? extends ObservableSource<? extends T>> sourceSupplier, Consumer<? super D> disposer, boolean eager) {
         ObjectHelper.requireNonNull(resourceSupplier, "resourceSupplier is null");
@@ -3460,6 +3567,7 @@ public static <T, D> Observable<T> using(Callable<? extends D> resourceSupplier,
      * @return the new Observable instance or the same as the source
      * @throws NullPointerException if source is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Observable<T> wrap(ObservableSource<T> source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -3514,6 +3622,7 @@ public static <T> Observable<T> wrap(ObservableSource<T> source) {
      * @return an Observable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> zip(Iterable<? extends ObservableSource<? extends T>> sources, Function<? super Object[], ? extends R> zipper) {
         ObjectHelper.requireNonNull(zipper, "zipper is null");
@@ -3567,6 +3676,7 @@ public static <T, R> Observable<R> zip(Iterable<? extends ObservableSource<? ext
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> zip(ObservableSource<? extends ObservableSource<? extends T>> sources, final Function<? super Object[], ? extends R> zipper) {
         ObjectHelper.requireNonNull(zipper, "zipper is null");
@@ -3620,6 +3730,7 @@ public static <T, R> Observable<R> zip(ObservableSource<? extends ObservableSour
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -3673,6 +3784,7 @@ public static <T1, T2, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -3727,6 +3839,7 @@ public static <T1, T2, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2,
@@ -3783,6 +3896,7 @@ public static <T1, T2, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -3842,6 +3956,7 @@ public static <T1, T2, T3, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -3905,6 +4020,7 @@ public static <T1, T2, T3, T4, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -3970,6 +4086,7 @@ public static <T1, T2, T3, T4, T5, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -4038,6 +4155,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -4110,6 +4228,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -4185,6 +4304,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> zip(
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> zip(
             ObservableSource<? extends T1> source1, ObservableSource<? extends T2> source2, ObservableSource<? extends T3> source3,
@@ -4244,6 +4364,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> zip(
      * @return an Observable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> zipArray(Function<? super Object[], ? extends R> zipper,
             boolean delayError, int bufferSize, ObservableSource<? extends T>... sources) {
@@ -4305,6 +4426,7 @@ public static <T, R> Observable<R> zipArray(Function<? super Object[], ? extends
      * @return an Observable that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Observable<R> zipIterable(Iterable<? extends ObservableSource<? extends T>> sources,
             Function<? super Object[], ? extends R> zipper, boolean delayError,
@@ -4335,6 +4457,7 @@ public static <T, R> Observable<R> zipIterable(Iterable<? extends ObservableSour
      *         predicate; otherwise, {@code false}
      * @see <a href="http://reactivex.io/documentation/operators/all.html">ReactiveX operators documentation: All</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> all(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -4358,6 +4481,7 @@ public final Single<Boolean> all(Predicate<? super T> predicate) {
      * @see <a href="http://reactivex.io/documentation/operators/amb.html">ReactiveX operators documentation: Amb</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> ambWith(ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -4384,6 +4508,7 @@ public final Observable<T> ambWith(ObservableSource<? extends T> other) {
      *         ObservableSource satisfies the {@code predicate}
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> any(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -4403,6 +4528,7 @@ public final Single<Boolean> any(Predicate<? super T> predicate) {
      *             if this {@code Observable} emits no items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingFirst() {
         BlockingFirstObserver<T> s = new BlockingFirstObserver<T>();
@@ -4428,6 +4554,7 @@ public final T blockingFirst() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingFirst(T defaultItem) {
         BlockingFirstObserver<T> s = new BlockingFirstObserver<T>();
@@ -4489,6 +4616,7 @@ public final void blockingForEach(Consumer<? super T> onNext) {
      * @return an {@link Iterable} version of this {@code Observable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingIterable() {
         return blockingIterable(bufferSize());
@@ -4507,6 +4635,7 @@ public final Iterable<T> blockingIterable() {
      * @return an {@link Iterable} version of this {@code Observable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingIterable(int bufferSize) {
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -4528,6 +4657,7 @@ public final Iterable<T> blockingIterable(int bufferSize) {
      *             if this {@code Observable} emits no items
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX documentation: Last</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingLast() {
         BlockingLastObserver<T> s = new BlockingLastObserver<T>();
@@ -4555,6 +4685,7 @@ public final T blockingLast() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX documentation: Last</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingLast(T defaultItem) {
         BlockingLastObserver<T> s = new BlockingLastObserver<T>();
@@ -4580,6 +4711,7 @@ public final T blockingLast(T defaultItem) {
      * @return an Iterable that always returns the latest item emitted by this {@code Observable}
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingLatest() {
         return new BlockingObservableLatest<T>(this);
@@ -4602,6 +4734,7 @@ public final Iterable<T> blockingLatest() {
      *         has most recently emitted
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingMostRecent(T initialValue) {
         return new BlockingObservableMostRecent<T>(this, initialValue);
@@ -4621,6 +4754,7 @@ public final Iterable<T> blockingMostRecent(T initialValue) {
      *         a new item, whereupon the Iterable returns that item
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Iterable<T> blockingNext() {
         return new BlockingObservableNext<T>(this);
@@ -4639,6 +4773,7 @@ public final Iterable<T> blockingNext() {
      * @return the single item emitted by this {@code Observable}
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingSingle() {
         T v = singleElement().blockingGet();
@@ -4665,6 +4800,7 @@ public final T blockingSingle() {
      *         items
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingSingle(T defaultItem) {
         return single(defaultItem).blockingGet();
@@ -4688,6 +4824,7 @@ public final T blockingSingle(T defaultItem) {
      * @return a {@link Future} that expects a single item to be emitted by this {@code Observable}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Future<T> toFuture() {
         return subscribeWith(new FutureObserver<T>());
@@ -4786,6 +4923,7 @@ public final void blockingSubscribe(Observer<? super T> subscriber) {
      *         {@code count} items from the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<List<T>> buffer(int count) {
         return buffer(count, count);
@@ -4813,6 +4951,7 @@ public final Observable<List<T>> buffer(int count) {
      *         containing at most {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<List<T>> buffer(int count, int skip) {
         return buffer(count, skip, ArrayListSupplier.<T>asCallable());
@@ -4844,6 +4983,7 @@ public final Observable<List<T>> buffer(int count, int skip) {
      *         containing at most {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Observable<U> buffer(int count, int skip, Callable<U> bufferSupplier) {
         ObjectHelper.verifyPositive(count, "count");
@@ -4874,6 +5014,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
      *         {@code count} items from the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Observable<U> buffer(int count, Callable<U> bufferSupplier) {
         return buffer(count, count, bufferSupplier);
@@ -4902,6 +5043,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, C
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<List<T>> buffer(long timespan, long timeskip, TimeUnit unit) {
         return buffer(timespan, timeskip, unit, Schedulers.computation(), ArrayListSupplier.<T>asCallable());
@@ -4932,6 +5074,7 @@ public final Observable<List<T>> buffer(long timespan, long timeskip, TimeUnit u
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<List<T>> buffer(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler) {
         return buffer(timespan, timeskip, unit, scheduler, ArrayListSupplier.<T>asCallable());
@@ -4966,6 +5109,7 @@ public final Observable<List<T>> buffer(long timespan, long timeskip, TimeUnit u
      *         a fixed timespan has elapsed
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <U extends Collection<? super T>> Observable<U> buffer(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler, Callable<U> bufferSupplier) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -4995,6 +5139,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(long timespa
      *         ObservableSource within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<List<T>> buffer(long timespan, TimeUnit unit) {
         return buffer(timespan, unit, Schedulers.computation(), Integer.MAX_VALUE);
@@ -5025,6 +5170,7 @@ public final Observable<List<T>> buffer(long timespan, TimeUnit unit) {
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<List<T>> buffer(long timespan, TimeUnit unit, int count) {
         return buffer(timespan, unit, Schedulers.computation(), count);
@@ -5058,6 +5204,7 @@ public final Observable<List<T>> buffer(long timespan, TimeUnit unit, int count)
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler scheduler, int count) {
         return buffer(timespan, unit, scheduler, count, ArrayListSupplier.<T>asCallable(), false);
@@ -5097,6 +5244,7 @@ public final Observable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler
      *         first)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <U extends Collection<? super T>> Observable<U> buffer(
             long timespan, TimeUnit unit,
@@ -5134,6 +5282,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(
      *         ObservableSource within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler scheduler) {
         return buffer(timespan, unit, scheduler, Integer.MAX_VALUE, ArrayListSupplier.<T>asCallable(), false);
@@ -5161,6 +5310,7 @@ public final Observable<List<T>> buffer(long timespan, TimeUnit unit, Scheduler
      *         and closed when the specified ObservableSources emit items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TOpening, TClosing> Observable<List<T>> buffer(
             ObservableSource<? extends TOpening> openingIndicator,
@@ -5194,6 +5344,7 @@ public final <TOpening, TClosing> Observable<List<T>> buffer(
      *         and closed when the specified ObservableSources emit items
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TOpening, TClosing, U extends Collection<? super T>> Observable<U> buffer(
             ObservableSource<? extends TOpening> openingIndicator,
@@ -5227,6 +5378,7 @@ public final <TOpening, TClosing, U extends Collection<? super T>> Observable<U>
      * @see #buffer(ObservableSource, int)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<List<T>> buffer(ObservableSource<B> boundary) {
         return buffer(boundary, ArrayListSupplier.<T>asCallable());
@@ -5256,6 +5408,7 @@ public final <B> Observable<List<T>> buffer(ObservableSource<B> boundary) {
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      * @see #buffer(ObservableSource)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<List<T>> buffer(ObservableSource<B> boundary, final int initialCapacity) {
         return buffer(boundary, Functions.<T>createArrayList(initialCapacity));
@@ -5287,6 +5440,7 @@ public final <B> Observable<List<T>> buffer(ObservableSource<B> boundary, final
      * @see #buffer(ObservableSource, int)
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B, U extends Collection<? super T>> Observable<U> buffer(ObservableSource<B> boundary, Callable<U> bufferSupplier) {
         ObjectHelper.requireNonNull(boundary, "boundary is null");
@@ -5314,6 +5468,7 @@ public final <B, U extends Collection<? super T>> Observable<U> buffer(Observabl
      *         each time the ObservableSource created with the {@code closingIndicator} argument emits an item
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<List<T>> buffer(Callable<? extends ObservableSource<B>> boundarySupplier) {
         return buffer(boundarySupplier, ArrayListSupplier.<T>asCallable());
@@ -5344,6 +5499,7 @@ public final <B> Observable<List<T>> buffer(Callable<? extends ObservableSource<
      *         each time the ObservableSource created with the {@code closingIndicator} argument emits an item
      * @see <a href="http://reactivex.io/documentation/operators/buffer.html">ReactiveX operators documentation: Buffer</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B, U extends Collection<? super T>> Observable<U> buffer(Callable<? extends ObservableSource<B>> boundarySupplier, Callable<U> bufferSupplier) {
         ObjectHelper.requireNonNull(boundarySupplier, "boundarySupplier is null");
@@ -5399,6 +5555,7 @@ public final <B, U extends Collection<? super T>> Observable<U> buffer(Callable<
      *         benefit of subsequent subscribers
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> cache() {
         return ObservableCache.from(this);
@@ -5456,6 +5613,7 @@ public final Observable<T> cache() {
      *         benefit of subsequent subscribers
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> cacheWithInitialCapacity(int initialCapacity) {
         return ObservableCache.from(this, initialCapacity);
@@ -5479,6 +5637,7 @@ public final Observable<T> cacheWithInitialCapacity(int initialCapacity) {
      *         specified type
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> cast(final Class<U> clazz) {
         ObjectHelper.requireNonNull(clazz, "clazz is null");
@@ -5507,6 +5666,7 @@ public final <U> Observable<U> cast(final Class<U> clazz) {
      *         into a single mutable data structure
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<U> collect(Callable<? extends U> initialValueSupplier, BiConsumer<? super U, ? super T> collector) {
         ObjectHelper.requireNonNull(initialValueSupplier, "initialValueSupplier is null");
@@ -5536,6 +5696,7 @@ public final <U> Single<U> collect(Callable<? extends U> initialValueSupplier, B
      *         into a single mutable data structure
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<U> collectInto(final U initialValue, BiConsumer<? super U, ? super T> collector) {
         ObjectHelper.requireNonNull(initialValue, "initialValue is null");
@@ -5561,6 +5722,7 @@ public final <U> Single<U> collectInto(final U initialValue, BiConsumer<? super
      * @return the source ObservableSource, transformed by the transformer function
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> compose(ObservableTransformer<T, R> composer) {
         return wrap(composer.apply(this));
@@ -5585,6 +5747,7 @@ public final <R> Observable<R> compose(ObservableTransformer<T, R> composer) {
      *         by the source ObservableSource and concatenating the ObservableSources obtained from this transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMap(mapper, 2);
@@ -5611,6 +5774,7 @@ public final <R> Observable<R> concatMap(Function<? super T, ? extends Observabl
      *         by the source ObservableSource and concatenating the ObservableSources obtained from this transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper, int prefetch) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -5641,6 +5805,7 @@ public final <R> Observable<R> concatMap(Function<? super T, ? extends Observabl
      * @param mapper the function that maps the items of this ObservableSource into the inner ObservableSources.
      * @return the new ObservableSource instance with the concatenation behavior
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMapDelayError(mapper, bufferSize(), true);
@@ -5666,6 +5831,7 @@ public final <R> Observable<R> concatMapDelayError(Function<? super T, ? extends
      *            if false, an error from the main source is signalled when the current ObservableSource source terminates
      * @return the new ObservableSource instance with the concatenation behavior
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             int prefetch, boolean tillTheEnd) {
@@ -5698,6 +5864,7 @@ public final <R> Observable<R> concatMapDelayError(Function<? super T, ? extends
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapEager(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMapEager(mapper, Integer.MAX_VALUE, bufferSize());
@@ -5722,6 +5889,7 @@ public final <R> Observable<R> concatMapEager(Function<? super T, ? extends Obse
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapEager(Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             int maxConcurrency, int prefetch) {
@@ -5751,6 +5919,7 @@ public final <R> Observable<R> concatMapEager(Function<? super T, ? extends Obse
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapEagerDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean tillTheEnd) {
@@ -5781,6 +5950,7 @@ public final <R> Observable<R> concatMapEagerDelayError(Function<? super T, ? ex
      * @return the new ObservableSource instance with the specified concatenation behavior
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> concatMapEagerDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             int maxConcurrency, int prefetch, boolean tillTheEnd) {
@@ -5806,6 +5976,7 @@ public final <R> Observable<R> concatMapEagerDelayError(Function<? super T, ? ex
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> concatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -5833,6 +6004,7 @@ public final <U> Observable<U> concatMapIterable(final Function<? super T, ? ext
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> concatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper, int prefetch) {
         return concatMap(ObservableInternalHelper.flatMapIntoIterable(mapper), prefetch);
@@ -5854,6 +6026,7 @@ public final <U> Observable<U> concatMapIterable(final Function<? super T, ? ext
      *         without interleaving them
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> concatWith(ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -5876,6 +6049,7 @@ public final Observable<T> concatWith(ObservableSource<? extends T> other) {
      *         or {@code false} if the source ObservableSource completes without emitting that item
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> contains(final Object element) {
         ObjectHelper.requireNonNull(element, "element is null");
@@ -5897,6 +6071,7 @@ public final Single<Boolean> contains(final Object element) {
      * @see <a href="http://reactivex.io/documentation/operators/count.html">ReactiveX operators documentation: Count</a>
      * @see #count()
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Long> count() {
         return RxJavaPlugins.onAssembly(new ObservableCountSingle<T>(this));
@@ -5920,6 +6095,7 @@ public final Single<Long> count() {
      *         within a computed debounce duration
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> debounce(Function<? super T, ? extends ObservableSource<U>> debounceSelector) {
         ObjectHelper.requireNonNull(debounceSelector, "debounceSelector is null");
@@ -5958,6 +6134,7 @@ public final <U> Observable<T> debounce(Function<? super T, ? extends Observable
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      * @see #throttleWithTimeout(long, TimeUnit)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> debounce(long timeout, TimeUnit unit) {
         return debounce(timeout, unit, Schedulers.computation());
@@ -5998,6 +6175,7 @@ public final Observable<T> debounce(long timeout, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      * @see #throttleWithTimeout(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> debounce(long timeout, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -6021,6 +6199,7 @@ public final Observable<T> debounce(long timeout, TimeUnit unit, Scheduler sched
      *         items, or the items emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> defaultIfEmpty(T defaultItem) {
         ObjectHelper.requireNonNull(defaultItem, "defaultItem is null");
@@ -6050,6 +6229,7 @@ public final Observable<T> defaultIfEmpty(T defaultItem) {
      *         per-item basis
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> delay(final Function<? super T, ? extends ObservableSource<U>> itemDelay) {
         ObjectHelper.requireNonNull(itemDelay, "itemDelay is null");
@@ -6073,6 +6253,7 @@ public final <U> Observable<T> delay(final Function<? super T, ? extends Observa
      * @return the source ObservableSource shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> delay(long delay, TimeUnit unit) {
         return delay(delay, unit, Schedulers.computation(), false);
@@ -6098,6 +6279,7 @@ public final Observable<T> delay(long delay, TimeUnit unit) {
      * @return the source ObservableSource shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> delay(long delay, TimeUnit unit, boolean delayError) {
         return delay(delay, unit, Schedulers.computation(), delayError);
@@ -6122,6 +6304,7 @@ public final Observable<T> delay(long delay, TimeUnit unit, boolean delayError)
      * @return the source ObservableSource shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
         return delay(delay, unit, scheduler, false);
@@ -6149,6 +6332,7 @@ public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler)
      * @return the source ObservableSource shifted in time by the specified delay
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler, boolean delayError) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -6185,6 +6369,7 @@ public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler,
      *         ObservableSource on a per-item basis
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<T> delay(ObservableSource<U> subscriptionDelay,
             Function<? super T, ? extends ObservableSource<V>> itemDelay) {
@@ -6208,6 +6393,7 @@ public final <U, V> Observable<T> delay(ObservableSource<U> subscriptionDelay,
      *         until the other Observable emits an element or completes normally.
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> delaySubscription(ObservableSource<U> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -6230,6 +6416,7 @@ public final <U> Observable<T> delaySubscription(ObservableSource<U> other) {
      * @return an Observable that delays the subscription to the source ObservableSource by the given amount
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> delaySubscription(long delay, TimeUnit unit) {
         return delaySubscription(delay, unit, Schedulers.computation());
@@ -6255,6 +6442,7 @@ public final Observable<T> delaySubscription(long delay, TimeUnit unit) {
      *         amount, waiting and subscribing on the given Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> delaySubscription(long delay, TimeUnit unit, Scheduler scheduler) {
         return delaySubscription(timer(delay, unit, scheduler));
@@ -6276,6 +6464,7 @@ public final Observable<T> delaySubscription(long delay, TimeUnit unit, Schedule
      *         emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/materialize-dematerialize.html">ReactiveX operators documentation: Dematerialize</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T2> Observable<T2> dematerialize() {
         @SuppressWarnings("unchecked")
@@ -6296,6 +6485,7 @@ public final <T2> Observable<T2> dematerialize() {
      *         each other
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> distinct() {
         return distinct(Functions.identity(), Functions.createHashSet());
@@ -6318,6 +6508,7 @@ public final Observable<T> distinct() {
      * @return an Observable that emits those items emitted by the source ObservableSource that have distinct keys
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Observable<T> distinct(Function<? super T, K> keySelector) {
         return distinct(keySelector, Functions.createHashSet());
@@ -6343,6 +6534,7 @@ public final <K> Observable<T> distinct(Function<? super T, K> keySelector) {
      * @return an Observable that emits those items emitted by the source ObservableSource that have distinct keys
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Observable<T> distinct(Function<? super T, K> keySelector, Callable<? extends Collection<? super K>> collectionSupplier) {
         ObjectHelper.requireNonNull(keySelector, "keySelector is null");
@@ -6364,6 +6556,7 @@ public final <K> Observable<T> distinct(Function<? super T, K> keySelector, Call
      *         immediate predecessors
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> distinctUntilChanged() {
         return distinctUntilChanged(Functions.identity());
@@ -6387,6 +6580,7 @@ public final Observable<T> distinctUntilChanged() {
      *         those of their immediate predecessors
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Observable<T> distinctUntilChanged(Function<? super T, K> keySelector) {
         ObjectHelper.requireNonNull(keySelector, "keySelector is null");
@@ -6410,6 +6604,7 @@ public final <K> Observable<T> distinctUntilChanged(Function<? super T, K> keySe
      * @see <a href="http://reactivex.io/documentation/operators/distinct.html">ReactiveX operators documentation: Distinct</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> distinctUntilChanged(BiPredicate<? super T, ? super T> comparer) {
         ObjectHelper.requireNonNull(comparer, "comparer is null");
@@ -6430,6 +6625,7 @@ public final Observable<T> distinctUntilChanged(BiPredicate<? super T, ? super T
      * @return the new Observable instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Observable<T> doAfterNext(Consumer<? super T> onAfterNext) {
@@ -6454,6 +6650,7 @@ public final Observable<T> doAfterNext(Consumer<? super T> onAfterNext) {
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      * @see #doOnTerminate(Action)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doAfterTerminate(Action onFinally) {
         ObjectHelper.requireNonNull(onFinally, "onFinally is null");
@@ -6477,6 +6674,7 @@ public final Observable<T> doAfterTerminate(Action onFinally) {
      * @return the new Observable instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Observable<T> doFinally(Action onFinally) {
@@ -6506,6 +6704,7 @@ public final Observable<T> doFinally(Action onFinally) {
      * @return the source {@code ObservableSource} modified so as to call this Action when appropriate
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnDispose(Action onDispose) {
         return doOnLifecycle(Functions.emptyConsumer(), onDispose);
@@ -6525,6 +6724,7 @@ public final Observable<T> doOnDispose(Action onDispose) {
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnComplete(Action onComplete) {
         return doOnEach(Functions.emptyConsumer(), Functions.emptyConsumer(), onComplete, Functions.EMPTY_ACTION);
@@ -6543,6 +6743,7 @@ public final Observable<T> doOnComplete(Action onComplete) {
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     private Observable<T> doOnEach(Consumer<? super T> onNext, Consumer<? super Throwable> onError, Action onComplete, Action onAfterTerminate) {
         ObjectHelper.requireNonNull(onNext, "onNext is null");
@@ -6566,6 +6767,7 @@ private Observable<T> doOnEach(Consumer<? super T> onNext, Consumer<? super Thro
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnEach(final Consumer<? super Notification<T>> onNotification) {
         ObjectHelper.requireNonNull(onNotification, "consumer is null");
@@ -6597,6 +6799,7 @@ public final Observable<T> doOnEach(final Consumer<? super Notification<T>> onNo
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnEach(final Observer<? super T> observer) {
         ObjectHelper.requireNonNull(observer, "observer is null");
@@ -6624,6 +6827,7 @@ public final Observable<T> doOnEach(final Observer<? super T> observer) {
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnError(Consumer<? super Throwable> onError) {
         return doOnEach(Functions.emptyConsumer(), onError, Functions.EMPTY_ACTION, Functions.EMPTY_ACTION);
@@ -6646,6 +6850,7 @@ public final Observable<T> doOnError(Consumer<? super Throwable> onError) {
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnLifecycle(final Consumer<? super Disposable> onSubscribe, final Action onDispose) {
         ObjectHelper.requireNonNull(onSubscribe, "onSubscribe is null");
@@ -6667,6 +6872,7 @@ public final Observable<T> doOnLifecycle(final Consumer<? super Disposable> onSu
      * @return the source ObservableSource with the side-effecting behavior applied
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnNext(Consumer<? super T> onNext) {
         return doOnEach(onNext, Functions.emptyConsumer(), Functions.EMPTY_ACTION, Functions.EMPTY_ACTION);
@@ -6689,6 +6895,7 @@ public final Observable<T> doOnNext(Consumer<? super T> onNext) {
      * @return the source {@code ObservableSource} modified so as to call this Consumer when appropriate
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnSubscribe(Consumer<? super Disposable> onSubscribe) {
         return doOnLifecycle(onSubscribe, Functions.EMPTY_ACTION);
@@ -6713,6 +6920,7 @@ public final Observable<T> doOnSubscribe(Consumer<? super Disposable> onSubscrib
      * @see <a href="http://reactivex.io/documentation/operators/do.html">ReactiveX operators documentation: Do</a>
      * @see #doAfterTerminate(Action)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> doOnTerminate(final Action onTerminate) {
         ObjectHelper.requireNonNull(onTerminate, "onTerminate is null");
@@ -6739,6 +6947,7 @@ public final Observable<T> doOnTerminate(final Action onTerminate) {
      *             if {@code index} is less than 0
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> elementAt(long index) {
         if (index < 0) {
@@ -6767,6 +6976,7 @@ public final Maybe<T> elementAt(long index) {
      *             if {@code index} is less than 0
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> elementAt(long index, T defaultItem) {
         if (index < 0) {
@@ -6794,6 +7004,7 @@ public final Single<T> elementAt(long index, T defaultItem) {
      *             if {@code index} is less than 0
      * @see <a href="http://reactivex.io/documentation/operators/elementat.html">ReactiveX operators documentation: ElementAt</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> elementAtOrError(long index) {
         if (index < 0) {
@@ -6818,6 +7029,7 @@ public final Single<T> elementAtOrError(long index) {
      *         evaluates as {@code true}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> filter(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -6837,6 +7049,7 @@ public final Observable<T> filter(Predicate<? super T> predicate) {
      * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> firstElement() {
         return elementAt(0L);
@@ -6857,6 +7070,7 @@ public final Maybe<T> firstElement() {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> first(T defaultItem) {
         return elementAt(0L, defaultItem);
@@ -6875,6 +7089,7 @@ public final Single<T> first(T defaultItem) {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> firstOrError() {
         return elementAtOrError(0L);
@@ -6900,6 +7115,7 @@ public final Single<T> firstOrError() {
      *         transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return flatMap(mapper, false);
@@ -6928,6 +7144,7 @@ public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableS
      *         transformation
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors) {
         return flatMap(mapper, delayErrors, Integer.MAX_VALUE);
@@ -6960,6 +7177,7 @@ public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableS
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
         return flatMap(mapper, delayErrors, maxConcurrency, bufferSize());
@@ -6994,6 +7212,7 @@ public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableS
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean delayErrors, int maxConcurrency, int bufferSize) {
@@ -7035,6 +7254,7 @@ public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableS
      *         specified functions to the emissions and notifications of the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(
             Function<? super T, ? extends ObservableSource<? extends R>> onNextMapper,
@@ -7074,6 +7294,7 @@ public final <R> Observable<R> flatMap(
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(
             Function<? super T, ? extends ObservableSource<? extends R>> onNextMapper,
@@ -7110,6 +7331,7 @@ public final <R> Observable<R> flatMap(
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper, int maxConcurrency) {
         return flatMap(mapper, false, maxConcurrency, bufferSize());
@@ -7138,6 +7360,7 @@ public final <R> Observable<R> flatMap(Function<? super T, ? extends ObservableS
      *         source ObservableSource and the collection ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends R> resultSelector) {
@@ -7170,6 +7393,7 @@ public final <U, R> Observable<R> flatMap(Function<? super T, ? extends Observab
      *         source ObservableSource and the collection ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors) {
@@ -7206,6 +7430,7 @@ public final <U, R> Observable<R> flatMap(Function<? super T, ? extends Observab
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency) {
@@ -7244,6 +7469,7 @@ public final <U, R> Observable<R> flatMap(Function<? super T, ? extends Observab
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> flatMap(final Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             final BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency, int bufferSize) {
@@ -7279,6 +7505,7 @@ public final <U, R> Observable<R> flatMap(final Function<? super T, ? extends Ob
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> flatMap(Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends R> combiner, int maxConcurrency) {
@@ -7295,6 +7522,7 @@ public final <U, R> Observable<R> flatMap(Function<? super T, ? extends Observab
      * @param mapper the function that received each source value and transforms them into CompletableSources.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(Function<? super T, ? extends CompletableSource> mapper) {
         return flatMapCompletable(mapper, false);
@@ -7312,6 +7540,7 @@ public final Completable flatMapCompletable(Function<? super T, ? extends Comple
      * terminates.
      * @return the new Completable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(Function<? super T, ? extends CompletableSource> mapper, boolean delayErrors) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -7337,6 +7566,7 @@ public final Completable flatMapCompletable(Function<? super T, ? extends Comple
      *         the values in the Iterables corresponding to those items, as generated by {@code collectionSelector}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -7367,6 +7597,7 @@ public final <U> Observable<U> flatMapIterable(final Function<? super T, ? exten
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<V> flatMapIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper,
             BiFunction<? super T, ? super U, ? extends V> resultSelector) {
@@ -7386,6 +7617,7 @@ public final <U, V> Observable<V> flatMapIterable(final Function<? super T, ? ex
      * @param mapper the function that received each source value and transforms them into MaybeSources.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapMaybe(Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return flatMapMaybe(mapper, false);
@@ -7406,6 +7638,7 @@ public final <R> Observable<R> flatMapMaybe(Function<? super T, ? extends MaybeS
      * terminates.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapMaybe(Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -7425,6 +7658,7 @@ public final <R> Observable<R> flatMapMaybe(Function<? super T, ? extends MaybeS
      * @param mapper the function that received each source value and transforms them into SingleSources.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapSingle(Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return flatMapSingle(mapper, false);
@@ -7445,6 +7679,7 @@ public final <R> Observable<R> flatMapSingle(Function<? super T, ? extends Singl
      * terminates.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapSingle(Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -7468,6 +7703,7 @@ public final <R> Observable<R> flatMapSingle(Function<? super T, ? extends Singl
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEach(Consumer<? super T> onNext) {
         return subscribe(onNext);
@@ -7489,6 +7725,7 @@ public final Disposable forEach(Consumer<? super T> onNext) {
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(Predicate<? super T> onNext) {
         return forEachWhile(onNext, Functions.ERROR_CONSUMER, Functions.EMPTY_ACTION);
@@ -7513,6 +7750,7 @@ public final Disposable forEachWhile(Predicate<? super T> onNext) {
      *             if {@code onError} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(Predicate<? super T> onNext, Consumer<? super Throwable> onError) {
         return forEachWhile(onNext, onError, Functions.EMPTY_ACTION);
@@ -7540,6 +7778,7 @@ public final Disposable forEachWhile(Predicate<? super T> onNext, Consumer<? sup
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable forEachWhile(final Predicate<? super T> onNext, Consumer<? super Throwable> onError,
             final Action onComplete) {
@@ -7580,6 +7819,7 @@ public final Disposable forEachWhile(final Predicate<? super T> onNext, Consumer
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Observable<GroupedObservable<K, T>> groupBy(Function<? super T, ? extends K> keySelector) {
         return groupBy(keySelector, (Function)Functions.identity(), false, bufferSize());
@@ -7616,6 +7856,7 @@ public final <K> Observable<GroupedObservable<K, T>> groupBy(Function<? super T,
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
     @SuppressWarnings({ "unchecked", "rawtypes" })
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Observable<GroupedObservable<K, T>> groupBy(Function<? super T, ? extends K> keySelector, boolean delayError) {
         return groupBy(keySelector, (Function)Functions.identity(), delayError, bufferSize());
@@ -7652,6 +7893,7 @@ public final <K> Observable<GroupedObservable<K, T>> groupBy(Function<? super T,
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
             Function<? super T, ? extends V> valueSelector) {
@@ -7692,6 +7934,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
             Function<? super T, ? extends V> valueSelector, boolean delayError) {
@@ -7734,6 +7977,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super
      *         key value
      * @see <a href="http://reactivex.io/documentation/operators/groupby.html">ReactiveX operators documentation: GroupBy</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super T, ? extends K> keySelector,
             Function<? super T, ? extends V> valueSelector,
@@ -7776,6 +8020,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(Function<? super
      *         whose durations overlap
      * @see <a href="http://reactivex.io/documentation/operators/join.html">ReactiveX operators documentation: Join</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> groupJoin(
             ObservableSource<? extends TRight> other,
@@ -7800,6 +8045,7 @@ public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> groupJoin(
      *
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> hide() {
         return RxJavaPlugins.onAssembly(new ObservableHide<T>(this));
@@ -7817,6 +8063,7 @@ public final Observable<T> hide() {
      * @return the new Completable instance
      * @see <a href="http://reactivex.io/documentation/operators/ignoreelements.html">ReactiveX operators documentation: IgnoreElements</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable ignoreElements() {
         return RxJavaPlugins.onAssembly(new ObservableIgnoreElementsCompletable<T>(this));
@@ -7837,6 +8084,7 @@ public final Completable ignoreElements() {
      * @return a Single that emits a Boolean
      * @see <a href="http://reactivex.io/documentation/operators/contains.html">ReactiveX operators documentation: Contains</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> isEmpty() {
         return all(Functions.alwaysFalse());
@@ -7873,6 +8121,7 @@ public final Single<Boolean> isEmpty() {
      *         overlapping durations
      * @see <a href="http://reactivex.io/documentation/operators/join.html">ReactiveX operators documentation: Join</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> join(
             ObservableSource<? extends TRight> other,
@@ -7898,6 +8147,7 @@ public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> join(
      *         error
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> lastElement() {
         return RxJavaPlugins.onAssembly(new ObservableLastMaybe<T>(this));
@@ -7919,6 +8169,7 @@ public final Maybe<T> lastElement() {
      *         if the source ObservableSource is empty
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> last(T defaultItem) {
         ObjectHelper.requireNonNull(defaultItem, "defaultItem is null");
@@ -7939,6 +8190,7 @@ public final Single<T> last(T defaultItem) {
      *         If the source ObservableSource completes without emitting any items a {@link NoSuchElementException} will be thrown.
      * @see <a href="http://reactivex.io/documentation/operators/last.html">ReactiveX operators documentation: Last</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> lastOrError() {
         return RxJavaPlugins.onAssembly(new ObservableLastSingle<T>(this, null));
@@ -7970,6 +8222,7 @@ public final Single<T> lastOrError() {
      * @return an Observable that is the result of applying the lifted Operator to the source ObservableSource
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> lift(ObservableOperator<? extends R, ? super T> lifter) {
         ObjectHelper.requireNonNull(lifter, "onLift is null");
@@ -7993,6 +8246,7 @@ public final <R> Observable<R> lift(ObservableOperator<? extends R, ? super T> l
      *         function
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> map(Function<? super T, ? extends R> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -8013,6 +8267,7 @@ public final <R> Observable<R> map(Function<? super T, ? extends R> mapper) {
      *         of the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/materialize-dematerialize.html">ReactiveX operators documentation: Materialize</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Notification<T>> materialize() {
         return RxJavaPlugins.onAssembly(new ObservableMaterialize<T>(this));
@@ -8035,6 +8290,7 @@ public final Observable<Notification<T>> materialize() {
      * @return an Observable that emits all of the items emitted by the source ObservableSources
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> mergeWith(ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -8055,7 +8311,7 @@ public final Observable<T> mergeWith(ObservableSource<? extends T> other) {
      * </dl>
      * <p>"Island size" indicates how large chunks the unbounded buffer allocates to store the excess elements waiting to be consumed
      * on the other side of the asynchronous boundary.
-     * 
+     *
      * @param scheduler
      *            the {@link Scheduler} to notify {@link Observer}s on
      * @return the source ObservableSource modified so that its {@link Observer}s are notified on the specified
@@ -8066,6 +8322,7 @@ public final Observable<T> mergeWith(ObservableSource<? extends T> other) {
      * @see #observeOn(Scheduler, boolean)
      * @see #observeOn(Scheduler, boolean, int)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> observeOn(Scheduler scheduler) {
         return observeOn(scheduler, false, bufferSize());
@@ -8097,6 +8354,7 @@ public final Observable<T> observeOn(Scheduler scheduler) {
      * @see #observeOn(Scheduler)
      * @see #observeOn(Scheduler, boolean, int)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> observeOn(Scheduler scheduler, boolean delayError) {
         return observeOn(scheduler, delayError, bufferSize());
@@ -8129,6 +8387,7 @@ public final Observable<T> observeOn(Scheduler scheduler, boolean delayError) {
      * @see #observeOn(Scheduler)
      * @see #observeOn(Scheduler, boolean)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> observeOn(Scheduler scheduler, boolean delayError, int bufferSize) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -8151,6 +8410,7 @@ public final Observable<T> observeOn(Scheduler scheduler, boolean delayError, in
      * @return an Observable that emits items from the source ObservableSource of type {@code clazz}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> ofType(final Class<U> clazz) {
         ObjectHelper.requireNonNull(clazz, "clazz is null");
@@ -8186,6 +8446,7 @@ public final <U> Observable<U> ofType(final Class<U> clazz) {
      * @return the original ObservableSource, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onErrorResumeNext(Function<? super Throwable, ? extends ObservableSource<? extends T>> resumeFunction) {
         ObjectHelper.requireNonNull(resumeFunction, "resumeFunction is null");
@@ -8221,6 +8482,7 @@ public final Observable<T> onErrorResumeNext(Function<? super Throwable, ? exten
      * @return the original ObservableSource, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onErrorResumeNext(final ObservableSource<? extends T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -8253,6 +8515,7 @@ public final Observable<T> onErrorResumeNext(final ObservableSource<? extends T>
      * @return the original ObservableSource with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onErrorReturn(Function<? super Throwable, ? extends T> valueSupplier) {
         ObjectHelper.requireNonNull(valueSupplier, "valueSupplier is null");
@@ -8285,6 +8548,7 @@ public final Observable<T> onErrorReturn(Function<? super Throwable, ? extends T
      * @return the original ObservableSource with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onErrorReturnItem(final T item) {
         ObjectHelper.requireNonNull(item, "item is null");
@@ -8323,6 +8587,7 @@ public final Observable<T> onErrorReturnItem(final T item) {
      * @return the original ObservableSource, with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onExceptionResumeNext(final ObservableSource<? extends T> next) {
         ObjectHelper.requireNonNull(next, "next is null");
@@ -8340,6 +8605,7 @@ public final Observable<T> onExceptionResumeNext(final ObservableSource<? extend
      * the sequence is terminated or downstream calls dispose()
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> onTerminateDetach() {
         return RxJavaPlugins.onAssembly(new ObservableDetach<T>(this));
@@ -8360,6 +8626,7 @@ public final Observable<T> onTerminateDetach() {
      *         to its {@link Observer}s
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableObservable<T> publish() {
         return ObservablePublish.create(this);
@@ -8384,6 +8651,7 @@ public final ConnectableObservable<T> publish() {
      * @return an Observable that emits the results of invoking the selector on the items emitted by a {@link ConnectableObservable} that shares a single subscription to the underlying sequence
      * @see <a href="http://reactivex.io/documentation/operators/publish.html">ReactiveX operators documentation: Publish</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> publish(Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
         ObjectHelper.requireNonNull(selector, "selector is null");
@@ -8414,6 +8682,7 @@ public final <R> Observable<R> publish(Function<? super Observable<T>, ? extends
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
         return scan(reducer).takeLast(1).singleElement();
@@ -8460,6 +8729,7 @@ public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
         return RxJavaPlugins.onAssembly(new ObservableSingleSingle<R>(scan(seed, reducer).takeLast(1), null));
@@ -8506,6 +8776,7 @@ public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> reduceWith(Callable<R> seedSupplier, BiFunction<R, ? super T, R> reducer) {
         return RxJavaPlugins.onAssembly(new ObservableSingleSingle<R>(scanWith(seedSupplier, reducer).takeLast(1), null));
@@ -8523,6 +8794,7 @@ public final <R> Single<R> reduceWith(Callable<R> seedSupplier, BiFunction<R, ?
      * @return an Observable that emits the items emitted by the source ObservableSource repeatedly and in sequence
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> repeat() {
         return repeat(Long.MAX_VALUE);
@@ -8547,6 +8819,7 @@ public final Observable<T> repeat() {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> repeat(long times) {
         if (times < 0) {
@@ -8576,6 +8849,7 @@ public final Observable<T> repeat(long times) {
      *             if {@code stop} is null
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> repeatUntil(BooleanSupplier stop) {
         ObjectHelper.requireNonNull(stop, "stop is null");
@@ -8601,6 +8875,7 @@ public final Observable<T> repeatUntil(BooleanSupplier stop) {
      * @return the source ObservableSource modified with repeat logic
      * @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> repeatWhen(final Function<? super Observable<Object>, ? extends ObservableSource<?>> handler) {
         ObjectHelper.requireNonNull(handler, "handler is null");
@@ -8623,6 +8898,7 @@ public final Observable<T> repeatWhen(final Function<? super Observable<Object>,
      *         items to its {@link Observer}s
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableObservable<T> replay() {
         return ObservableReplay.createFrom(this);
@@ -8647,6 +8923,7 @@ public final ConnectableObservable<T> replay() {
      *         {@link ConnectableObservable} that shares a single subscription to the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
         ObjectHelper.requireNonNull(selector, "selector is null");
@@ -8676,6 +8953,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *         replaying no more than {@code bufferSize} items
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final int bufferSize) {
         ObjectHelper.requireNonNull(selector, "selector is null");
@@ -8710,6 +8988,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *         {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, TimeUnit unit) {
         return replay(selector, bufferSize, time, unit, Schedulers.computation());
@@ -8747,6 +9026,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *             if {@code bufferSize} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final int bufferSize, final long time, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -8780,6 +9060,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *         replaying no more than {@code bufferSize} notifications
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Observable<R> replay(final Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final int bufferSize, final Scheduler scheduler) {
         return ObservableReplay.multicastSelector(ObservableInternalHelper.replayCallable(this, bufferSize),
@@ -8811,6 +9092,7 @@ public final <R> Observable<R> replay(final Function<? super Observable<T>, ? ex
      *         replaying all items that were emitted within the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, TimeUnit unit) {
         return replay(selector, time, unit, Schedulers.computation());
@@ -8843,6 +9125,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *         replaying all items that were emitted within the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final long time, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(selector, "selector is null");
@@ -8873,6 +9156,7 @@ public final <R> Observable<R> replay(Function<? super Observable<T>, ? extends
      *         replaying all items
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <R> Observable<R> replay(final Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(selector, "selector is null");
@@ -8899,6 +9183,7 @@ public final <R> Observable<R> replay(final Function<? super Observable<T>, ? ex
      *         replays at most {@code bufferSize} items emitted by that ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final ConnectableObservable<T> replay(final int bufferSize) {
         return ObservableReplay.create(this, bufferSize);
@@ -8927,6 +9212,7 @@ public final ConnectableObservable<T> replay(final int bufferSize) {
      *         {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final ConnectableObservable<T> replay(int bufferSize, long time, TimeUnit unit) {
         return replay(bufferSize, time, unit, Schedulers.computation());
@@ -8959,6 +9245,7 @@ public final ConnectableObservable<T> replay(int bufferSize, long time, TimeUnit
      *             if {@code bufferSize} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableObservable<T> replay(final int bufferSize, final long time, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -8987,6 +9274,7 @@ public final ConnectableObservable<T> replay(final int bufferSize, final long ti
      *         replays at most {@code bufferSize} items that were emitted by the ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableObservable<T> replay(final int bufferSize, final Scheduler scheduler) {
         return ObservableReplay.observeOn(replay(bufferSize), scheduler);
@@ -9012,6 +9300,7 @@ public final ConnectableObservable<T> replay(final int bufferSize, final Schedul
      *         replays the items that were emitted during the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final ConnectableObservable<T> replay(long time, TimeUnit unit) {
         return replay(time, unit, Schedulers.computation());
@@ -9039,6 +9328,7 @@ public final ConnectableObservable<T> replay(long time, TimeUnit unit) {
      *         replays the items that were emitted during the window defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableObservable<T> replay(final long time, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -9065,6 +9355,7 @@ public final ConnectableObservable<T> replay(final long time, final TimeUnit uni
      *         {@link Scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final ConnectableObservable<T> replay(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -9092,6 +9383,7 @@ public final ConnectableObservable<T> replay(final Scheduler scheduler) {
      * @return the source ObservableSource modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retry() {
         return retry(Long.MAX_VALUE, Functions.alwaysTrue());
@@ -9114,6 +9406,7 @@ public final Observable<T> retry() {
      * @see #retry()
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retry(BiPredicate<? super Integer, ? super Throwable> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -9145,6 +9438,7 @@ public final Observable<T> retry(BiPredicate<? super Integer, ? super Throwable>
      * @return the source ObservableSource modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retry(long times) {
         return retry(times, Functions.alwaysTrue());
@@ -9162,6 +9456,7 @@ public final Observable<T> retry(long times) {
      * @param predicate the predicate called with the failure Throwable and should return true to trigger a retry.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retry(long times, Predicate<? super Throwable> predicate) {
         if (times < 0) {
@@ -9184,6 +9479,7 @@ public final Observable<T> retry(long times, Predicate<? super Throwable> predic
      * @param predicate the predicate that receives the failure Throwable and should return true to trigger a retry.
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retry(Predicate<? super Throwable> predicate) {
         return retry(Long.MAX_VALUE, predicate);
@@ -9199,6 +9495,7 @@ public final Observable<T> retry(Predicate<? super Throwable> predicate) {
      * @param stop the function that should return true to stop retrying
      * @return the new Observable instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retryUntil(final BooleanSupplier stop) {
         ObjectHelper.requireNonNull(stop, "stop is null");
@@ -9253,6 +9550,7 @@ public final Observable<T> retryUntil(final BooleanSupplier stop) {
      * @return the source ObservableSource modified with retry logic
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> retryWhen(
             final Function<? super Observable<Throwable>, ? extends ObservableSource<?>> handler) {
@@ -9301,6 +9599,7 @@ public final void safeSubscribe(Observer<? super T> s) {
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see #throttleLast(long, TimeUnit)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> sample(long period, TimeUnit unit) {
         return sample(period, unit, Schedulers.computation());
@@ -9327,6 +9626,7 @@ public final Observable<T> sample(long period, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see #throttleLast(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> sample(long period, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -9353,6 +9653,7 @@ public final Observable<T> sample(long period, TimeUnit unit, Scheduler schedule
      *         the {@code sampler} ObservableSource emits an item or completes
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> sample(ObservableSource<U> sampler) {
         ObjectHelper.requireNonNull(sampler, "sampler is null");
@@ -9380,6 +9681,7 @@ public final <U> Observable<T> sample(ObservableSource<U> sampler) {
      * @return an Observable that emits the results of each call to the accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> scan(BiFunction<T, T, T> accumulator) {
         ObjectHelper.requireNonNull(accumulator, "accumulator is null");
@@ -9428,6 +9730,7 @@ public final Observable<T> scan(BiFunction<T, T, T> accumulator) {
      *         accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> scan(final R initialValue, BiFunction<R, ? super T, R> accumulator) {
         ObjectHelper.requireNonNull(initialValue, "seed is null");
@@ -9476,6 +9779,7 @@ public final <R> Observable<R> scan(final R initialValue, BiFunction<R, ? super
      *         accumulator function
      * @see <a href="http://reactivex.io/documentation/operators/scan.html">ReactiveX operators documentation: Scan</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> scanWith(Callable<R> seedSupplier, BiFunction<R, ? super T, R> accumulator) {
         ObjectHelper.requireNonNull(seedSupplier, "seedSupplier is null");
@@ -9503,6 +9807,7 @@ public final <R> Observable<R> scanWith(Callable<R> seedSupplier, BiFunction<R,
      *         its observers
      * @see <a href="http://reactivex.io/documentation/operators/serialize.html">ReactiveX operators documentation: Serialize</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> serialize() {
         return RxJavaPlugins.onAssembly(new ObservableSerialized<T>(this));
@@ -9525,6 +9830,7 @@ public final Observable<T> serialize() {
      *         to its {@link Observer}s
      * @see <a href="http://reactivex.io/documentation/operators/refcount.html">ReactiveX operators documentation: RefCount</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> share() {
         return publish().refCount();
@@ -9544,6 +9850,7 @@ public final Observable<T> share() {
      * @return an Observable that emits the single item emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> singleElement() {
         return RxJavaPlugins.onAssembly(new ObservableSingleMaybe<T>(this));
@@ -9565,6 +9872,7 @@ public final Maybe<T> singleElement() {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> single(T defaultItem) {
         ObjectHelper.requireNonNull(defaultItem, "defaultItem is null");
@@ -9586,6 +9894,7 @@ public final Single<T> single(T defaultItem) {
      * @return the new Single instance
      * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX operators documentation: First</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> singleOrError() {
         return RxJavaPlugins.onAssembly(new ObservableSingleSingle<T>(this, null));
@@ -9607,6 +9916,7 @@ public final Single<T> singleOrError() {
      *         {@code count} items that the source ObservableSource emits
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> skip(long count) {
         if (count <= 0) {
@@ -9634,6 +9944,7 @@ public final Observable<T> skip(long count) {
      *         by {@code time} elapses and the emits the remainder
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> skip(long time, TimeUnit unit) {
         return skipUntil(timer(time, unit));
@@ -9659,6 +9970,7 @@ public final Observable<T> skip(long time, TimeUnit unit) {
      *         by {@code time} and {@code scheduler} elapses, and then emits the remainder
      * @see <a href="http://reactivex.io/documentation/operators/skip.html">ReactiveX operators documentation: Skip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> skip(long time, TimeUnit unit, Scheduler scheduler) {
         return skipUntil(timer(time, unit, scheduler));
@@ -9686,6 +9998,7 @@ public final Observable<T> skip(long time, TimeUnit unit, Scheduler scheduler) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> skipLast(int count) {
         if (count < 0) {
@@ -9718,6 +10031,7 @@ public final Observable<T> skipLast(int count) {
      *         source completes defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.TRAMPOLINE)
     public final Observable<T> skipLast(long time, TimeUnit unit) {
         return skipLast(time, unit, Schedulers.trampoline(), false, bufferSize());
@@ -9747,6 +10061,7 @@ public final Observable<T> skipLast(long time, TimeUnit unit) {
      *         source completes defined by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.TRAMPOLINE)
     public final Observable<T> skipLast(long time, TimeUnit unit, boolean delayError) {
         return skipLast(time, unit, Schedulers.trampoline(), delayError, bufferSize());
@@ -9774,6 +10089,7 @@ public final Observable<T> skipLast(long time, TimeUnit unit, boolean delayError
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler) {
         return skipLast(time, unit, scheduler, false, bufferSize());
@@ -9804,6 +10120,7 @@ public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler schedule
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError) {
         return skipLast(time, unit, scheduler, delayError, bufferSize());
@@ -9836,6 +10153,7 @@ public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler schedule
      *         source completes defined by {@code time} and {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -9864,6 +10182,7 @@ public final Observable<T> skipLast(long time, TimeUnit unit, Scheduler schedule
      *         item, then emits the remaining items
      * @see <a href="http://reactivex.io/documentation/operators/skipuntil.html">ReactiveX operators documentation: SkipUntil</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> skipUntil(ObservableSource<U> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -9886,6 +10205,7 @@ public final <U> Observable<T> skipUntil(ObservableSource<U> other) {
      *         predicate becomes false
      * @see <a href="http://reactivex.io/documentation/operators/skipwhile.html">ReactiveX operators documentation: SkipWhile</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> skipWhile(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -9910,6 +10230,7 @@ public final Observable<T> skipWhile(Predicate<? super T> predicate) {
      * </dl>
      * @return an Observable that emits the items emitted by the source ObservableSource in sorted order
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> sorted() {
         return toList().toObservable().map(Functions.listSorter(Functions.<T>naturalComparator())).flatMapIterable(Functions.<List<T>>identity());
@@ -9932,6 +10253,7 @@ public final Observable<T> sorted() {
      *            that indicates their sort order
      * @return an Observable that emits the items emitted by the source ObservableSource in sorted order
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> sorted(Comparator<? super T> sortFunction) {
         return toList().toObservable().map(Functions.listSorter(sortFunction)).flatMapIterable(Functions.<List<T>>identity());
@@ -9954,6 +10276,7 @@ public final Observable<T> sorted(Comparator<? super T> sortFunction) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> startWith(Iterable<? extends T> items) {
         return concatArray(fromIterable(items), this);
@@ -9976,6 +10299,7 @@ public final Observable<T> startWith(Iterable<? extends T> items) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> startWith(ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -9999,6 +10323,7 @@ public final Observable<T> startWith(ObservableSource<? extends T> other) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> startWith(T item) {
         ObjectHelper.requireNonNull(item, "item is null");
@@ -10022,6 +10347,7 @@ public final Observable<T> startWith(T item) {
      * @see <a href="http://reactivex.io/documentation/operators/startwith.html">ReactiveX operators documentation: StartWith</a>
      */
     @SuppressWarnings("unchecked")
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> startWithArray(T... items) {
         Observable<T> fromArray = fromArray(items);
@@ -10066,6 +10392,7 @@ public final Disposable subscribe() {
      *             if {@code onNext} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext) {
         return subscribe(onNext, Functions.ERROR_CONSUMER, Functions.EMPTY_ACTION, Functions.emptyConsumer());
@@ -10091,6 +10418,7 @@ public final Disposable subscribe(Consumer<? super T> onNext) {
      *             if {@code onNext} is null, or
      *             if {@code onError} is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError) {
         return subscribe(onNext, onError, Functions.EMPTY_ACTION, Functions.emptyConsumer());
@@ -10120,6 +10448,7 @@ public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super T
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
             Action onComplete) {
@@ -10152,6 +10481,7 @@ public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super T
      *             if {@code onComplete} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
             Action onComplete, Consumer<? super Disposable> onSubscribe) {
@@ -10248,6 +10578,7 @@ public final <E extends Observer<? super T>> E subscribeWith(E observer) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #observeOn
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> subscribeOn(Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -10269,6 +10600,7 @@ public final Observable<T> subscribeOn(Scheduler scheduler) {
      *          alternate ObservableSource if the source ObservableSource is empty.
      * @since 1.1.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> switchIfEmpty(ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -10296,6 +10628,7 @@ public final Observable<T> switchIfEmpty(ObservableSource<? extends T> other) {
      * @return an Observable that emits the items emitted by the ObservableSource returned from applying {@code func} to the most recently emitted item emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> switchMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return switchMap(mapper, bufferSize());
@@ -10324,6 +10657,7 @@ public final <R> Observable<R> switchMap(Function<? super T, ? extends Observabl
      * @return an Observable that emits the items emitted by the ObservableSource returned from applying {@code func} to the most recently emitted item emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> switchMap(Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -10362,6 +10696,7 @@ public final <R> Observable<R> switchMap(Function<? super T, ? extends Observabl
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> switchMapDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return switchMapDelayError(mapper, bufferSize());
@@ -10392,6 +10727,7 @@ public final <R> Observable<R> switchMapDelayError(Function<? super T, ? extends
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> switchMapDelayError(Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -10427,6 +10763,7 @@ public final <R> Observable<R> switchMapDelayError(Function<? super T, ? extends
      *         all of the items from the source ObservableSource if that ObservableSource emits fewer than {@code count} items
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> take(long count) {
         if (count < 0) {
@@ -10452,6 +10789,7 @@ public final Observable<T> take(long count) {
      * @return an Observable that emits those items emitted by the source ObservableSource before the time runs out
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> take(long time, TimeUnit unit) {
         return takeUntil(timer(time, unit));
@@ -10477,6 +10815,7 @@ public final Observable<T> take(long time, TimeUnit unit) {
      *         according to the specified Scheduler
      * @see <a href="http://reactivex.io/documentation/operators/take.html">ReactiveX operators documentation: Take</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> take(long time, TimeUnit unit, Scheduler scheduler) {
         return takeUntil(timer(time, unit, scheduler));
@@ -10500,6 +10839,7 @@ public final Observable<T> take(long time, TimeUnit unit, Scheduler scheduler) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> takeLast(int count) {
         if (count < 0) {
@@ -10535,6 +10875,7 @@ public final Observable<T> takeLast(int count) {
      *         in a specified window of time before the ObservableSource completed
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.TRAMPOLINE)
     public final Observable<T> takeLast(long count, long time, TimeUnit unit) {
         return takeLast(count, time, unit, Schedulers.trampoline(), false, bufferSize());
@@ -10566,6 +10907,7 @@ public final Observable<T> takeLast(long count, long time, TimeUnit unit) {
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> takeLast(long count, long time, TimeUnit unit, Scheduler scheduler) {
         return takeLast(count, time, unit, scheduler, false, bufferSize());
@@ -10602,6 +10944,7 @@ public final Observable<T> takeLast(long count, long time, TimeUnit unit, Schedu
      *             if {@code count} is less than zero
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> takeLast(long count, long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -10631,6 +10974,7 @@ public final Observable<T> takeLast(long count, long time, TimeUnit unit, Schedu
      *         time before the ObservableSource completed specified by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.TRAMPOLINE)
     public final Observable<T> takeLast(long time, TimeUnit unit) {
         return takeLast(time, unit, Schedulers.trampoline(), false, bufferSize());
@@ -10657,6 +11001,7 @@ public final Observable<T> takeLast(long time, TimeUnit unit) {
      *         time before the ObservableSource completed specified by {@code time}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.TRAMPOLINE)
     public final Observable<T> takeLast(long time, TimeUnit unit, boolean delayError) {
         return takeLast(time, unit, Schedulers.trampoline(), delayError, bufferSize());
@@ -10684,6 +11029,7 @@ public final Observable<T> takeLast(long time, TimeUnit unit, boolean delayError
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler) {
         return takeLast(time, unit, scheduler, false, bufferSize());
@@ -10714,6 +11060,7 @@ public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler schedule
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError) {
         return takeLast(time, unit, scheduler, delayError, bufferSize());
@@ -10746,6 +11093,7 @@ public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler schedule
      *         provided by {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler scheduler, boolean delayError, int bufferSize) {
         return takeLast(Long.MAX_VALUE, time, unit, scheduler, delayError, bufferSize);
@@ -10769,6 +11117,7 @@ public final Observable<T> takeLast(long time, TimeUnit unit, Scheduler schedule
      * @return an Observable that emits the items emitted by the source Observable until such time as {@code other} emits its first item
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<T> takeUntil(ObservableSource<U> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -10797,6 +11146,7 @@ public final <U> Observable<T> takeUntil(ObservableSource<U> other) {
      * @see Observable#takeWhile(Predicate)
      * @since 1.1.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> takeUntil(Predicate<? super T> stopPredicate) {
         ObjectHelper.requireNonNull(stopPredicate, "predicate is null");
@@ -10820,6 +11170,7 @@ public final Observable<T> takeUntil(Predicate<? super T> stopPredicate) {
      * @see <a href="http://reactivex.io/documentation/operators/takewhile.html">ReactiveX operators documentation: TakeWhile</a>
      * @see Observable#takeUntil(Predicate)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> takeWhile(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -10846,6 +11197,7 @@ public final Observable<T> takeWhile(Predicate<? super T> predicate) {
      * @return an Observable that performs the throttle operation
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> throttleFirst(long windowDuration, TimeUnit unit) {
         return throttleFirst(windowDuration, unit, Schedulers.computation());
@@ -10874,6 +11226,7 @@ public final Observable<T> throttleFirst(long windowDuration, TimeUnit unit) {
      * @return an Observable that performs the throttle operation
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> throttleFirst(long skipDuration, TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -10903,6 +11256,7 @@ public final Observable<T> throttleFirst(long skipDuration, TimeUnit unit, Sched
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see #sample(long, TimeUnit)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> throttleLast(long intervalDuration, TimeUnit unit) {
         return sample(intervalDuration, unit);
@@ -10933,6 +11287,7 @@ public final Observable<T> throttleLast(long intervalDuration, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/sample.html">ReactiveX operators documentation: Sample</a>
      * @see #sample(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> throttleLast(long intervalDuration, TimeUnit unit, Scheduler scheduler) {
         return sample(intervalDuration, unit, scheduler);
@@ -10969,6 +11324,7 @@ public final Observable<T> throttleLast(long intervalDuration, TimeUnit unit, Sc
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      * @see #debounce(long, TimeUnit)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> throttleWithTimeout(long timeout, TimeUnit unit) {
         return debounce(timeout, unit);
@@ -11009,6 +11365,7 @@ public final Observable<T> throttleWithTimeout(long timeout, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
      * @see #debounce(long, TimeUnit, Scheduler)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> throttleWithTimeout(long timeout, TimeUnit unit, Scheduler scheduler) {
         return debounce(timeout, unit, scheduler);
@@ -11028,6 +11385,7 @@ public final Observable<T> throttleWithTimeout(long timeout, TimeUnit unit, Sche
      * @return an Observable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Timed<T>> timeInterval() {
         return timeInterval(TimeUnit.MILLISECONDS, Schedulers.computation());
@@ -11049,6 +11407,7 @@ public final Observable<Timed<T>> timeInterval() {
      * @return an Observable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Observable<Timed<T>> timeInterval(Scheduler scheduler) {
         return timeInterval(TimeUnit.MILLISECONDS, scheduler);
@@ -11069,6 +11428,7 @@ public final Observable<Timed<T>> timeInterval(Scheduler scheduler) {
      * @return an Observable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE) // Trampoline scheduler is only used for creating timestamps.
     public final Observable<Timed<T>> timeInterval(TimeUnit unit) {
         return timeInterval(unit, Schedulers.computation());
@@ -11091,6 +11451,7 @@ public final Observable<Timed<T>> timeInterval(TimeUnit unit) {
      * @return an Observable that emits time interval information items
      * @see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Observable<Timed<T>> timeInterval(TimeUnit unit, Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -11122,6 +11483,7 @@ public final Observable<Timed<T>> timeInterval(TimeUnit unit, Scheduler schedule
      *         the time window defined by the selector for the previously emitted item
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <V> Observable<T> timeout(Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator) {
         return timeout0(null, itemTimeoutIndicator, null);
@@ -11153,6 +11515,7 @@ public final <V> Observable<T> timeout(Function<? super T, ? extends ObservableS
      *         by the selector for the previously emitted item
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <V> Observable<T> timeout(Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator,
             ObservableSource<? extends T> other) {
@@ -11179,6 +11542,7 @@ public final <V> Observable<T> timeout(Function<? super T, ? extends ObservableS
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> timeout(long timeout, TimeUnit timeUnit) {
         return timeout0(timeout, timeUnit, null, Schedulers.computation());
@@ -11204,6 +11568,7 @@ public final Observable<T> timeout(long timeout, TimeUnit timeUnit) {
      * @return the source ObservableSource modified to switch to the fallback ObservableSource in case of a timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<T> timeout(long timeout, TimeUnit timeUnit, ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -11233,6 +11598,7 @@ public final Observable<T> timeout(long timeout, TimeUnit timeUnit, ObservableSo
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler, ObservableSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -11261,6 +11627,7 @@ public final Observable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler sc
      *         timeout
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler scheduler) {
         return timeout0(timeout, timeUnit, null, scheduler);
@@ -11293,6 +11660,7 @@ public final Observable<T> timeout(long timeout, TimeUnit timeUnit, Scheduler sc
      *         the time windows specified by the timeout selectors
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<T> timeout(ObservableSource<U> firstTimeoutIndicator,
             Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator) {
@@ -11332,6 +11700,7 @@ public final <U, V> Observable<T> timeout(ObservableSource<U> firstTimeoutIndica
      *             if {@code other} is null
      * @see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<T> timeout(
             ObservableSource<U> firstTimeoutIndicator,
@@ -11371,6 +11740,7 @@ private <U, V> Observable<T> timeout0(
      * @return an Observable that emits timestamped items from the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Timed<T>> timestamp() {
         return timestamp(TimeUnit.MILLISECONDS, Schedulers.computation());
@@ -11393,6 +11763,7 @@ public final Observable<Timed<T>> timestamp() {
      *         the {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Observable<Timed<T>> timestamp(Scheduler scheduler) {
         return timestamp(TimeUnit.MILLISECONDS, scheduler);
@@ -11413,6 +11784,7 @@ public final Observable<Timed<T>> timestamp(Scheduler scheduler) {
      * @return an Observable that emits timestamped items from the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Timed<T>> timestamp(TimeUnit unit) {
         return timestamp(unit, Schedulers.computation());
@@ -11436,6 +11808,7 @@ public final Observable<Timed<T>> timestamp(TimeUnit unit) {
      *         the {@code scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/timestamp.html">ReactiveX operators documentation: Timestamp</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE) // Supplied scheduler is only used for creating timestamps.
     public final Observable<Timed<T>> timestamp(final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -11455,6 +11828,7 @@ public final Observable<Timed<T>> timestamp(final TimeUnit unit, final Scheduler
      * @param converter the function that receives the current Observable instance and returns a value
      * @return the value returned by the function
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> R to(Function<? super Observable<T>, R> converter) {
         try {
@@ -11488,6 +11862,7 @@ public final <R> R to(Function<? super Observable<T>, R> converter) {
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toList() {
         return toList(16);
@@ -11518,6 +11893,7 @@ public final Single<List<T>> toList() {
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toList(final int capacityHint) {
         ObjectHelper.verifyPositive(capacityHint, "capacityHint");
@@ -11550,6 +11926,7 @@ public final Single<List<T>> toList(final int capacityHint) {
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U extends Collection<? super T>> Single<U> toList(Callable<U> collectionSupplier) {
         ObjectHelper.requireNonNull(collectionSupplier, "collectionSupplier is null");
@@ -11575,6 +11952,7 @@ public final <U extends Collection<? super T>> Single<U> toList(Callable<U> coll
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Single<Map<K, T>> toMap(final Function<? super T, ? extends K> keySelector) {
         return collect(HashMapSupplier.<K, T>asCallable(), Functions.toMapKeySelector(keySelector));
@@ -11603,6 +11981,7 @@ public final <K> Single<Map<K, T>> toMap(final Function<? super T, ? extends K>
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, V>> toMap(
             final Function<? super T, ? extends K> keySelector,
@@ -11634,6 +12013,7 @@ public final <K, V> Single<Map<K, V>> toMap(
      *         source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, V>> toMap(
             final Function<? super T, ? extends K> keySelector,
@@ -11659,6 +12039,7 @@ public final <K, V> Single<Map<K, V>> toMap(
      *         the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K> Single<Map<K, Collection<T>>> toMultimap(Function<? super T, ? extends K> keySelector) {
         @SuppressWarnings({ "rawtypes", "unchecked" })
@@ -11689,6 +12070,7 @@ public final <K> Single<Map<K, Collection<T>>> toMultimap(Function<? super T, ?
      *         the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector) {
         Callable<Map<K, Collection<V>>> mapSupplier = HashMapSupplier.asCallable();
@@ -11721,6 +12103,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(Function<? super T,
      *         the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
             final Function<? super T, ? extends K> keySelector,
@@ -11757,6 +12140,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
             Function<? super T, ? extends K> keySelector,
@@ -11779,6 +12163,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
      * @return the new Flowable instance
      */
     @BackpressureSupport(BackpressureKind.SPECIAL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> toFlowable(BackpressureStrategy strategy) {
         Flowable<T> o = new FlowableFromObservable<T>(this);
@@ -11815,6 +12200,7 @@ public final Flowable<T> toFlowable(BackpressureStrategy strategy) {
      *         sorted order
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList() {
         return toSortedList(Functions.naturalOrder());
@@ -11837,6 +12223,7 @@ public final Single<List<T>> toSortedList() {
      *         sorted order
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(final Comparator<? super T> comparator) {
         ObjectHelper.requireNonNull(comparator, "comparator is null");
@@ -11863,6 +12250,7 @@ public final Single<List<T>> toSortedList(final Comparator<? super T> comparator
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(final Comparator<? super T> comparator, int capacityHint) {
         ObjectHelper.requireNonNull(comparator, "comparator is null");
@@ -11891,6 +12279,7 @@ public final Single<List<T>> toSortedList(final Comparator<? super T> comparator
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<List<T>> toSortedList(int capacityHint) {
         return toSortedList(Functions.<T>naturalOrder(), capacityHint);
@@ -11910,6 +12299,7 @@ public final Single<List<T>> toSortedList(int capacityHint) {
      *         {@link Scheduler}
      * @see <a href="http://reactivex.io/documentation/operators/subscribeon.html">ReactiveX operators documentation: SubscribeOn</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<T> unsubscribeOn(Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -11935,6 +12325,7 @@ public final Observable<T> unsubscribeOn(Scheduler scheduler) {
      * @throws IllegalArgumentException if either count is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Observable<T>> window(long count) {
         return window(count, count, bufferSize());
@@ -11962,6 +12353,7 @@ public final Observable<Observable<T>> window(long count) {
      * @throws IllegalArgumentException if either count or skip is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Observable<T>> window(long count, long skip) {
         return window(count, skip, bufferSize());
@@ -11991,6 +12383,7 @@ public final Observable<Observable<T>> window(long count, long skip) {
      * @throws IllegalArgumentException if either count or skip is non-positive
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<Observable<T>> window(long count, long skip, int bufferSize) {
         ObjectHelper.verifyPositive(count, "count");
@@ -12021,6 +12414,7 @@ public final Observable<Observable<T>> window(long count, long skip, int bufferS
      * @return an Observable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<Observable<T>> window(long timespan, long timeskip, TimeUnit unit) {
         return window(timespan, timeskip, unit, Schedulers.computation(), bufferSize());
@@ -12050,6 +12444,7 @@ public final Observable<Observable<T>> window(long timespan, long timeskip, Time
      * @return an Observable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler) {
         return window(timespan, timeskip, unit, scheduler, bufferSize());
@@ -12081,6 +12476,7 @@ public final Observable<Observable<T>> window(long timespan, long timeskip, Time
      * @return an Observable that emits new windows periodically as a fixed timespan elapses
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(long timespan, long timeskip, TimeUnit unit, Scheduler scheduler, int bufferSize) {
         ObjectHelper.verifyPositive(timespan, "timespan");
@@ -12112,6 +12508,7 @@ public final Observable<Observable<T>> window(long timespan, long timeskip, Time
      *         source ObservableSource during fixed, consecutive durations
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit) {
         return window(timespan, unit, Schedulers.computation(), Long.MAX_VALUE, false);
@@ -12142,6 +12539,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit) {
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
             long count) {
@@ -12175,6 +12573,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
             long count, boolean restart) {
@@ -12204,6 +12603,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
      *         source ObservableSource within a fixed duration
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
             Scheduler scheduler) {
@@ -12237,6 +12637,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
             Scheduler scheduler, long count) {
@@ -12272,6 +12673,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
             Scheduler scheduler, long count, boolean restart) {
@@ -12309,6 +12711,7 @@ public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
      *         (whichever occurs first)
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Observable<Observable<T>> window(
             long timespan, TimeUnit unit, Scheduler scheduler,
@@ -12340,6 +12743,7 @@ public final Observable<Observable<T>> window(
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<Observable<T>> window(ObservableSource<B> boundary) {
         return window(boundary, bufferSize());
@@ -12367,6 +12771,7 @@ public final <B> Observable<Observable<T>> window(ObservableSource<B> boundary)
      *         ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<Observable<T>> window(ObservableSource<B> boundary, int bufferSize) {
         ObjectHelper.requireNonNull(boundary, "boundary is null");
@@ -12396,6 +12801,7 @@ public final <B> Observable<Observable<T>> window(ObservableSource<B> boundary,
      *         the specified window-governing ObservableSources
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<Observable<T>> window(
             ObservableSource<U> openingIndicator,
@@ -12428,6 +12834,7 @@ public final <U, V> Observable<Observable<T>> window(
      *         the specified window-governing ObservableSources
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, V> Observable<Observable<T>> window(
             ObservableSource<U> openingIndicator,
@@ -12458,6 +12865,7 @@ public final <U, V> Observable<Observable<T>> window(
      *         whenever {@code closingIndicator} emits an item
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<Observable<T>> window(Callable<? extends ObservableSource<B>> boundary) {
         return window(boundary, bufferSize());
@@ -12485,6 +12893,7 @@ public final <B> Observable<Observable<T>> window(Callable<? extends ObservableS
      *         whenever {@code closingIndicator} emits an item
      * @see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <B> Observable<Observable<T>> window(Callable<? extends ObservableSource<B>> boundary, int bufferSize) {
         ObjectHelper.requireNonNull(boundary, "boundary is null");
@@ -12515,6 +12924,7 @@ public final <B> Observable<Observable<T>> window(Callable<? extends ObservableS
      * @since 2.0
      * @see <a href="http://reactivex.io/documentation/operators/combinelatest.html">ReactiveX operators documentation: CombineLatest</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> withLatestFrom(ObservableSource<? extends U> other, BiFunction<? super T, ? super U, ? extends R> combiner) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -12547,6 +12957,7 @@ public final <U, R> Observable<R> withLatestFrom(ObservableSource<? extends U> o
      * @return the new ObservableSource instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, R> Observable<R> withLatestFrom(
             ObservableSource<T1> o1, ObservableSource<T2> o2,
@@ -12584,6 +12995,7 @@ public final <T1, T2, R> Observable<R> withLatestFrom(
      * @return the new ObservableSource instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, T3, R> Observable<R> withLatestFrom(
             ObservableSource<T1> o1, ObservableSource<T2> o2,
@@ -12625,6 +13037,7 @@ public final <T1, T2, T3, R> Observable<R> withLatestFrom(
      * @return the new ObservableSource instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <T1, T2, T3, T4, R> Observable<R> withLatestFrom(
             ObservableSource<T1> o1, ObservableSource<T2> o2,
@@ -12660,6 +13073,7 @@ public final <T1, T2, T3, T4, R> Observable<R> withLatestFrom(
      * @return the new ObservableSource instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> withLatestFrom(ObservableSource<?>[] others, Function<? super Object[], R> combiner) {
         ObjectHelper.requireNonNull(others, "others is null");
@@ -12688,6 +13102,7 @@ public final <R> Observable<R> withLatestFrom(ObservableSource<?>[] others, Func
      * @return the new ObservableSource instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> withLatestFrom(Iterable<? extends ObservableSource<?>> others, Function<? super Object[], R> combiner) {
         ObjectHelper.requireNonNull(others, "others is null");
@@ -12721,6 +13136,7 @@ public final <R> Observable<R> withLatestFrom(Iterable<? extends ObservableSourc
      *         sequence and emits the results of {@code zipFunction} applied to these pairs
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> zipWith(Iterable<U> other,  BiFunction<? super T, ? super U, ? extends R> zipper) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -12763,6 +13179,7 @@ public final <U, R> Observable<R> zipWith(Iterable<U> other,  BiFunction<? super
      *         and emits the results of {@code zipFunction} applied to these pairs
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
             BiFunction<? super T, ? super U, ? extends R> zipper) {
@@ -12808,6 +13225,7 @@ public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
             BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError) {
@@ -12854,6 +13272,7 @@ public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Observable<R> zipWith(ObservableSource<? extends U> other,
             BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError, int bufferSize) {
@@ -12884,7 +13303,7 @@ public final TestObserver<T> test() { // NoPMD
     /**
      * Creates a TestObserver, optionally disposes it and then subscribes
      * it to this Observable.
-     * 
+     *
      * <dl>
      *  <dt><b>Scheduler:</b></dt>
      *  <dd>{@code test} does not operate by default on a particular {@link Scheduler}.</dd>
diff --git a/src/main/java/io/reactivex/Single.java b/src/main/java/io/reactivex/Single.java
index 2083171cb1..5e38eb0afb 100644
--- a/src/main/java/io/reactivex/Single.java
+++ b/src/main/java/io/reactivex/Single.java
@@ -70,6 +70,7 @@ public abstract class Single<T> implements SingleSource<T> {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> amb(final Iterable<? extends SingleSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -88,6 +89,7 @@ public static <T> Single<T> amb(final Iterable<? extends SingleSource<? extends
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Single<T> ambArray(final SingleSource<? extends T>... sources) {
@@ -114,6 +116,7 @@ public static <T> Single<T> ambArray(final SingleSource<? extends T>... sources)
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     public static <T> Flowable<T> concat(Iterable<? extends SingleSource<? extends T>> sources) {
@@ -132,6 +135,7 @@ public static <T> Flowable<T> concat(Iterable<? extends SingleSource<? extends T
      * @return the new Observable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Observable<T> concat(ObservableSource<? extends SingleSource<? extends T>> sources) {
@@ -153,6 +157,7 @@ public static <T> Observable<T> concat(ObservableSource<? extends SingleSource<?
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> concat(Publisher<? extends SingleSource<? extends T>> sources) {
@@ -175,6 +180,7 @@ public static <T> Flowable<T> concat(Publisher<? extends SingleSource<? extends
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
@@ -202,6 +208,7 @@ public static <T> Flowable<T> concat(Publisher<? extends SingleSource<? extends
      * @return a Flowable that emits items emitted by the two source Singles, one after the other.
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -234,6 +241,7 @@ public static <T> Flowable<T> concat(
      * @return a Flowable that emits items emitted by the three source Singles, one after the other.
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -270,6 +278,7 @@ public static <T> Flowable<T> concat(
      * @return a Flowable that emits items emitted by the four source Singles, one after the other.
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -298,6 +307,7 @@ public static <T> Flowable<T> concat(
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
@@ -340,6 +350,7 @@ public static <T> Flowable<T> concatArray(SingleSource<? extends T>... sources)
      * @see SingleOnSubscribe
      * @see Cancellable
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> create(SingleOnSubscribe<T> source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -358,6 +369,7 @@ public static <T> Single<T> create(SingleOnSubscribe<T> source) {
      * returns a SingleSource instance to subscribe to
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> defer(final Callable<? extends SingleSource<? extends T>> singleSupplier) {
         ObjectHelper.requireNonNull(singleSupplier, "singleSupplier is null");
@@ -375,6 +387,7 @@ public static <T> Single<T> defer(final Callable<? extends SingleSource<? extend
      * returns a Throwable instance to be emitted.
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> error(final Callable<? extends Throwable> errorSupplier) {
         ObjectHelper.requireNonNull(errorSupplier, "errorSupplier is null");
@@ -399,6 +412,7 @@ public static <T> Single<T> error(final Callable<? extends Throwable> errorSuppl
      *         the subscriber subscribes to it
      * @see <a href="http://reactivex.io/documentation/operators/empty-never-throw.html">ReactiveX operators documentation: Throw</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> error(final Throwable exception) {
         ObjectHelper.requireNonNull(exception, "error is null");
@@ -422,6 +436,7 @@ public static <T> Single<T> error(final Throwable exception) {
      *         the type of the item emitted by the {@link Single}.
      * @return a {@link Single} whose {@link SingleObserver}s' subscriptions trigger an invocation of the given function.
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> fromCallable(final Callable<? extends T> callable) {
         ObjectHelper.requireNonNull(callable, "callable is null");
@@ -451,6 +466,7 @@ public static <T> Single<T> fromCallable(final Callable<? extends T> callable) {
      * @return a {@code Single} that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> fromFuture(Future<? extends T> future) {
         return toSingle(Flowable.<T>fromFuture(future));
@@ -483,6 +499,7 @@ public static <T> Single<T> fromFuture(Future<? extends T> future) {
      * @return a {@code Single} that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit) {
         return toSingle(Flowable.<T>fromFuture(future, timeout, unit));
@@ -517,6 +534,7 @@ public static <T> Single<T> fromFuture(Future<? extends T> future, long timeout,
      * @return a {@code Single} that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Single<T> fromFuture(Future<? extends T> future, long timeout, TimeUnit unit, Scheduler scheduler) {
         return toSingle(Flowable.<T>fromFuture(future, timeout, unit, scheduler));
@@ -546,6 +564,7 @@ public static <T> Single<T> fromFuture(Future<? extends T> future, long timeout,
      * @return a {@code Single} that emits the item from the source {@link Future}
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static <T> Single<T> fromFuture(Future<? extends T> future, Scheduler scheduler) {
         return toSingle(Flowable.<T>fromFuture(future, scheduler));
@@ -567,6 +586,7 @@ public static <T> Single<T> fromFuture(Future<? extends T> future, Scheduler sch
      * @return the new Single instance
      */
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> fromPublisher(final Publisher<? extends T> publisher) {
         ObjectHelper.requireNonNull(publisher, "publisher is null");
@@ -588,6 +608,7 @@ public static <T> Single<T> fromPublisher(final Publisher<? extends T> publisher
      *         the type of the item emitted by the {@link Single}.
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> fromObservable(ObservableSource<? extends T> observableSource) {
         ObjectHelper.requireNonNull(observableSource, "observableSource is null");
@@ -613,6 +634,7 @@ public static <T> Single<T> fromObservable(ObservableSource<? extends T> observa
      * @return a {@code Single} that emits {@code item}
      * @see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> just(final T item) {
         ObjectHelper.requireNonNull(item, "value is null");
@@ -633,6 +655,7 @@ public static <T> Single<T> just(final T item) {
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> merge(Iterable<? extends SingleSource<? extends T>> sources) {
@@ -653,6 +676,7 @@ public static <T> Flowable<T> merge(Iterable<? extends SingleSource<? extends T>
      * @return the new Flowable instance
      * @since 2.0
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
@@ -678,6 +702,7 @@ public static <T> Flowable<T> merge(Publisher<? extends SingleSource<? extends T
      *         by {@code source}
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static <T> Single<T> merge(SingleSource<? extends SingleSource<? extends T>> source) {
@@ -707,6 +732,7 @@ public static <T> Single<T> merge(SingleSource<? extends SingleSource<? extends
      * @return a Flowable that emits all of the items emitted by the source Singles
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -742,6 +768,7 @@ public static <T> Flowable<T> merge(
      * @return a Flowable that emits all of the items emitted by the source Singles
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -781,6 +808,7 @@ public static <T> Flowable<T> merge(
      * @return a Flowable that emits all of the items emitted by the source Singles
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
+    @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
@@ -805,6 +833,7 @@ public static <T> Flowable<T> merge(
      * @return the singleton never instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T> Single<T> never() {
@@ -822,6 +851,7 @@ public static <T> Single<T> never() {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public static Single<Long> timer(long delay, TimeUnit unit) {
         return timer(delay, unit, Schedulers.computation());
@@ -839,6 +869,7 @@ public static Single<Long> timer(long delay, TimeUnit unit) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public static Single<Long> timer(final long delay, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -858,6 +889,7 @@ public static Single<Long> timer(final long delay, final TimeUnit unit, final Sc
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<Boolean> equals(final SingleSource<? extends T> first, final SingleSource<? extends T> second) { // NOPMD
         ObjectHelper.requireNonNull(first, "first is null");
@@ -880,6 +912,7 @@ public static <T> Single<Boolean> equals(final SingleSource<? extends T> first,
      * instead.
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> unsafeCreate(SingleSource<T> onSubscribe) {
         ObjectHelper.requireNonNull(onSubscribe, "onSubscribe is null");
@@ -908,6 +941,7 @@ public static <T> Single<T> unsafeCreate(SingleSource<T> onSubscribe) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, U> Single<T> using(Callable<U> resourceSupplier,
                                          Function<? super U, ? extends SingleSource<? extends T>> singleFunction,
@@ -937,6 +971,7 @@ public static <T, U> Single<T> using(Callable<U> resourceSupplier,
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, U> Single<T> using(
             final Callable<U> resourceSupplier,
@@ -961,6 +996,7 @@ public static <T, U> Single<T> using(
      * @param source the source to wrap
      * @return the Single wrapper or the source cast to Single (if possible)
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> wrap(SingleSource<T> source) {
         ObjectHelper.requireNonNull(source, "source is null");
@@ -996,6 +1032,7 @@ public static <T> Single<T> wrap(SingleSource<T> source) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T, R> Single<R> zip(final Iterable<? extends SingleSource<? extends T>> sources, Function<? super Object[], ? extends R> zipper) {
         ObjectHelper.requireNonNull(sources, "sources is null");
@@ -1025,6 +1062,7 @@ public static <T, R> Single<R> zip(final Iterable<? extends SingleSource<? exten
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, R> Single<R> zip(
@@ -1062,6 +1100,7 @@ public static <T1, T2, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, R> Single<R> zip(
@@ -1104,6 +1143,7 @@ public static <T1, T2, T3, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, R> Single<R> zip(
@@ -1150,6 +1190,7 @@ public static <T1, T2, T3, T4, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, T5, R> Single<R> zip(
@@ -1201,6 +1242,7 @@ public static <T1, T2, T3, T4, T5, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, T5, T6, R> Single<R> zip(
@@ -1256,6 +1298,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, T5, T6, T7, R> Single<R> zip(
@@ -1316,6 +1359,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Single<R> zip(
@@ -1380,6 +1424,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Single<R> zip(
      * @return a Single that emits the zipped results
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Single<R> zip(
@@ -1428,6 +1473,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Single<R> zip(
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({"rawtypes", "unchecked"})
     public static <T, R> Single<R> zipArray(Function<? super Object[], ? extends R> zipper, SingleSource<? extends T>... sources) {
@@ -1452,6 +1498,7 @@ public static <T, R> Single<R> zipArray(Function<? super Object[], ? extends R>
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public final Single<T> ambWith(SingleSource<? extends T> other) {
@@ -1469,6 +1516,7 @@ public final Single<T> ambWith(SingleSource<? extends T> other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> hide() {
         return RxJavaPlugins.onAssembly(new SingleHide<T>(this));
@@ -1492,6 +1540,7 @@ public final Single<T> hide() {
      * @return the source Single, transformed by the transformer function
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> compose(SingleTransformer<T, R> transformer) {
         return wrap(transformer.apply(this));
@@ -1509,6 +1558,7 @@ public final <R> Single<R> compose(SingleTransformer<T, R> transformer) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> cache() {
         return RxJavaPlugins.onAssembly(new SingleCache<T>(this));
@@ -1526,6 +1576,7 @@ public final Single<T> cache() {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<U> cast(final Class<? extends U> clazz) {
         ObjectHelper.requireNonNull(clazz, "clazz is null");
@@ -1551,6 +1602,7 @@ public final <U> Single<U> cast(final Class<? extends U> clazz) {
      * @see <a href="http://reactivex.io/documentation/operators/concat.html">ReactiveX operators documentation: Concat</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> concatWith(SingleSource<? extends T> other) {
         return concat(this, other);
@@ -1569,6 +1621,7 @@ public final Flowable<T> concatWith(SingleSource<? extends T> other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Single<T> delay(long time, TimeUnit unit) {
         return delay(time, unit, Schedulers.computation());
@@ -1588,6 +1641,7 @@ public final Single<T> delay(long time, TimeUnit unit) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Single<T> delay(final long time, final TimeUnit unit, final Scheduler scheduler) {
         ObjectHelper.requireNonNull(unit, "unit is null");
@@ -1609,6 +1663,7 @@ public final Single<T> delay(final long time, final TimeUnit unit, final Schedul
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> delaySubscription(CompletableSource other) {
         return RxJavaPlugins.onAssembly(new SingleDelayWithCompletable<T>(this, other));
@@ -1629,6 +1684,7 @@ public final Single<T> delaySubscription(CompletableSource other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<T> delaySubscription(SingleSource<U> other) {
         return RxJavaPlugins.onAssembly(new SingleDelayWithSingle<T, U>(this, other));
@@ -1649,6 +1705,7 @@ public final <U> Single<T> delaySubscription(SingleSource<U> other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<T> delaySubscription(ObservableSource<U> other) {
         return RxJavaPlugins.onAssembly(new SingleDelayWithObservable<T, U>(this, other));
@@ -1674,6 +1731,7 @@ public final <U> Single<T> delaySubscription(ObservableSource<U> other) {
      * @since 2.0
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Single<T> delaySubscription(Publisher<U> other) {
         return RxJavaPlugins.onAssembly(new SingleDelayWithPublisher<T, U>(this, other));
@@ -1692,6 +1750,7 @@ public final <U> Single<T> delaySubscription(Publisher<U> other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final <U> Single<T> delaySubscription(long time, TimeUnit unit) {
         return delaySubscription(time, unit, Schedulers.computation());
@@ -1711,6 +1770,7 @@ public final <U> Single<T> delaySubscription(long time, TimeUnit unit) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final <U> Single<T> delaySubscription(long time, TimeUnit unit, Scheduler scheduler) {
         return delaySubscription(Observable.timer(time, unit, scheduler));
@@ -1728,6 +1788,7 @@ public final <U> Single<T> delaySubscription(long time, TimeUnit unit, Scheduler
      * @return the new Single instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Single<T> doAfterSuccess(Consumer<? super T> onAfterSuccess) {
@@ -1750,6 +1811,7 @@ public final Single<T> doAfterSuccess(Consumer<? super T> onAfterSuccess) {
      * @return the new Single instance
      * @since 2.0.1 - experimental
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public final Single<T> doFinally(Action onFinally) {
@@ -1768,6 +1830,7 @@ public final Single<T> doFinally(Action onFinally) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> doOnSubscribe(final Consumer<? super Disposable> onSubscribe) {
         ObjectHelper.requireNonNull(onSubscribe, "onSubscribe is null");
@@ -1785,6 +1848,7 @@ public final Single<T> doOnSubscribe(final Consumer<? super Disposable> onSubscr
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> doOnSuccess(final Consumer<? super T> onSuccess) {
         ObjectHelper.requireNonNull(onSuccess, "onSuccess is null");
@@ -1802,6 +1866,7 @@ public final Single<T> doOnSuccess(final Consumer<? super T> onSuccess) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> doOnEvent(final BiConsumer<? super T, ? super Throwable> onEvent) {
         ObjectHelper.requireNonNull(onEvent, "onEvent is null");
@@ -1819,6 +1884,7 @@ public final Single<T> doOnEvent(final BiConsumer<? super T, ? super Throwable>
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> doOnError(final Consumer<? super Throwable> onError) {
         ObjectHelper.requireNonNull(onError, "onError is null");
@@ -1836,6 +1902,7 @@ public final Single<T> doOnError(final Consumer<? super Throwable> onError) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> doOnDispose(final Action onDispose) {
         ObjectHelper.requireNonNull(onDispose, "onDispose is null");
@@ -1859,6 +1926,7 @@ public final Single<T> doOnDispose(final Action onDispose) {
      *         evaluates as {@code true}
      * @see <a href="http://reactivex.io/documentation/operators/filter.html">ReactiveX operators documentation: Filter</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Maybe<T> filter(Predicate<? super T> predicate) {
         ObjectHelper.requireNonNull(predicate, "predicate is null");
@@ -1881,6 +1949,7 @@ public final Maybe<T> filter(Predicate<? super T> predicate) {
      * @return the Single returned from {@code mapper} when applied to the item emitted by the source Single
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> flatMap(Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -1903,6 +1972,7 @@ public final <R> Single<R> flatMap(Function<? super T, ? extends SingleSource<?
      * @return the Maybe returned from {@code mapper} when applied to the item emitted by the source Single
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Maybe<R> flatMapMaybe(final Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -1930,6 +2000,7 @@ public final <R> Maybe<R> flatMapMaybe(final Function<? super T, ? extends Maybe
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Flowable<R> flatMapPublisher(Function<? super T, ? extends Publisher<? extends R>> mapper) {
         return toFlowable().flatMap(mapper);
@@ -1956,6 +2027,7 @@ public final <R> Flowable<R> flatMapPublisher(Function<? super T, ? extends Publ
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Flowable<U> flattenAsFlowable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         return RxJavaPlugins.onAssembly(new SingleFlatMapIterableFlowable<T, U>(this, mapper));
@@ -1978,6 +2050,7 @@ public final <U> Flowable<U> flattenAsFlowable(final Function<? super T, ? exten
      * @return the new Observable instance
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U> Observable<U> flattenAsObservable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
         return RxJavaPlugins.onAssembly(new SingleFlatMapIterableObservable<T, U>(this, mapper));
@@ -1999,6 +2072,7 @@ public final <U> Observable<U> flattenAsObservable(final Function<? super T, ? e
      * @return the Observable returned from {@code func} when applied to the item emitted by the source Single
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Observable<R> flatMapObservable(Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return toObservable().flatMap(mapper);
@@ -2021,6 +2095,7 @@ public final <R> Observable<R> flatMapObservable(Function<? super T, ? extends O
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable flatMapCompletable(final Function<? super T, ? extends Completable> mapper) {
         ObjectHelper.requireNonNull(mapper, "mapper is null");
@@ -2036,6 +2111,7 @@ public final Completable flatMapCompletable(final Function<? super T, ? extends
      * </dl>
      * @return the success value
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final T blockingGet() {
         BlockingMultiObserver<T> observer = new BlockingMultiObserver<T>();
@@ -2066,6 +2142,7 @@ public final T blockingGet() {
      * @return a Single that is the result of applying the lifted Operator to the source Single
      * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators">RxJava wiki: Implementing Your Own Operators</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> lift(final SingleOperator<? extends R, ? super T> lift) {
         ObjectHelper.requireNonNull(lift, "onLift is null");
@@ -2088,6 +2165,7 @@ public final <R> Single<R> lift(final SingleOperator<? extends R, ? super T> lif
      * @return a Single that emits the item from the source Single, transformed by the specified function
      * @see <a href="http://reactivex.io/documentation/operators/map.html">ReactiveX operators documentation: Map</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> Single<R> map(Function<? super T, ? extends R> mapper) {
         return RxJavaPlugins.onAssembly(new SingleMap<T, R>(this, mapper));
@@ -2104,6 +2182,7 @@ public final <R> Single<R> map(Function<? super T, ? extends R> mapper) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> contains(Object value) {
         return contains(value, ObjectHelper.equalsPredicate());
@@ -2122,6 +2201,7 @@ public final Single<Boolean> contains(Object value) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<Boolean> contains(final Object value, final BiPredicate<Object, Object> comparer) {
         ObjectHelper.requireNonNull(value, "value is null");
@@ -2149,6 +2229,7 @@ public final Single<Boolean> contains(final Object value, final BiPredicate<Obje
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> mergeWith(SingleSource<? extends T> other) {
         return merge(this, other);
@@ -2172,6 +2253,7 @@ public final Flowable<T> mergeWith(SingleSource<? extends T> other) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #subscribeOn
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Single<T> observeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -2204,6 +2286,7 @@ public final Single<T> observeOn(final Scheduler scheduler) {
      * @return the original Single with appropriately modified behavior
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> onErrorReturn(final Function<Throwable, ? extends T> resumeFunction) {
         ObjectHelper.requireNonNull(resumeFunction, "resumeFunction is null");
@@ -2220,6 +2303,7 @@ public final Single<T> onErrorReturn(final Function<Throwable, ? extends T> resu
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> onErrorReturnItem(final T value) {
         ObjectHelper.requireNonNull(value, "value is null");
@@ -2253,6 +2337,7 @@ public final Single<T> onErrorReturnItem(final T value) {
      * @return the original Single, with appropriately modified behavior.
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> onErrorResumeNext(final Single<? extends T> resumeSingleInCaseOfError) {
         ObjectHelper.requireNonNull(resumeSingleInCaseOfError, "resumeSingleInCaseOfError is null");
@@ -2287,6 +2372,7 @@ public final Single<T> onErrorResumeNext(final Single<? extends T> resumeSingleI
      * @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
      * @since .20
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> onErrorResumeNext(
             final Function<? super Throwable, ? extends SingleSource<? extends T>> resumeFunctionInCaseOfError) {
@@ -2306,6 +2392,7 @@ public final Single<T> onErrorResumeNext(
      * @since 2.0
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat() {
         return toFlowable().repeat();
@@ -2324,6 +2411,7 @@ public final Flowable<T> repeat() {
      * @since 2.0
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeat(long times) {
         return toFlowable().repeat(times);
@@ -2348,6 +2436,7 @@ public final Flowable<T> repeat(long times) {
      * @since 2.0
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatWhen(Function<? super Flowable<Object>, ? extends Publisher<Object>> handler) {
         return toFlowable().repeatWhen(handler);
@@ -2367,6 +2456,7 @@ public final Flowable<T> repeatWhen(Function<? super Flowable<Object>, ? extends
      * @since 2.0
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> repeatUntil(BooleanSupplier stop) {
         return toFlowable().repeatUntil(stop);
@@ -2381,6 +2471,7 @@ public final Flowable<T> repeatUntil(BooleanSupplier stop) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> retry() {
         return toSingle(toFlowable().retry());
@@ -2397,6 +2488,7 @@ public final Single<T> retry() {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> retry(long times) {
         return toSingle(toFlowable().retry(times));
@@ -2414,6 +2506,7 @@ public final Single<T> retry(long times) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> retry(BiPredicate<? super Integer, ? super Throwable> predicate) {
         return toSingle(toFlowable().retry(predicate));
@@ -2431,6 +2524,7 @@ public final Single<T> retry(BiPredicate<? super Integer, ? super Throwable> pre
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> retry(Predicate<? super Throwable> predicate) {
         return toSingle(toFlowable().retry(predicate));
@@ -2452,6 +2546,7 @@ public final Single<T> retry(Predicate<? super Throwable> predicate) {
      *                be the output of the resulting Single
      * @return the new Single instance
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> retryWhen(Function<? super Flowable<Throwable>, ? extends Publisher<Object>> handler) {
         return toSingle(toFlowable().retryWhen(handler));
@@ -2488,6 +2583,7 @@ public final Disposable subscribe() {
      * @throws NullPointerException
      *             if {@code onCallback} is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(final BiConsumer<? super T, ? super Throwable> onCallback) {
         ObjectHelper.requireNonNull(onCallback, "onCallback is null");
@@ -2511,6 +2607,7 @@ public final Disposable subscribe(final BiConsumer<? super T, ? super Throwable>
      *             if {@code onSuccess} is null
      * @see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(Consumer<? super T> onSuccess) {
         return subscribe(onSuccess, Functions.ERROR_CONSUMER);
@@ -2535,6 +2632,7 @@ public final Disposable subscribe(Consumer<? super T> onSuccess) {
      *             if {@code onSuccess} is null, or
      *             if {@code onError} is null
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Disposable subscribe(final Consumer<? super T> onSuccess, final Consumer<? super Throwable> onError) {
         ObjectHelper.requireNonNull(onSuccess, "onSuccess is null");
@@ -2619,6 +2717,7 @@ public final <E extends SingleObserver<? super T>> E subscribeWith(E observer) {
      * @see <a href="http://www.grahamlea.com/2014/07/rxjava-threading-examples/">RxJava Threading Examples</a>
      * @see #observeOn
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Single<T> subscribeOn(final Scheduler scheduler) {
         ObjectHelper.requireNonNull(scheduler, "scheduler is null");
@@ -2642,6 +2741,7 @@ public final Single<T> subscribeOn(final Scheduler scheduler) {
      * @return a Single that emits the item emitted by the source Single until such time as {@code other} terminates.
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Single<T> takeUntil(final CompletableSource other) {
         return takeUntil(new CompletableToFlowable<T>(other));
@@ -2671,6 +2771,7 @@ public final Single<T> takeUntil(final CompletableSource other) {
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E> Single<T> takeUntil(final Publisher<E> other) {
         return RxJavaPlugins.onAssembly(new SingleTakeUntil<T, E>(this, other));
@@ -2694,6 +2795,7 @@ public final <E> Single<T> takeUntil(final Publisher<E> other) {
      * @return a Single that emits the item emitted by the source Single until such time as {@code other} emits its item
      * @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <E> Single<T> takeUntil(final SingleSource<? extends E> other) {
         return takeUntil(new SingleToFlowable<E>(other));
@@ -2711,6 +2813,7 @@ public final <E> Single<T> takeUntil(final SingleSource<? extends E> other) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Single<T> timeout(long timeout, TimeUnit unit) {
         return timeout0(timeout, unit, Schedulers.computation(), null);
@@ -2730,6 +2833,7 @@ public final Single<T> timeout(long timeout, TimeUnit unit) {
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Single<T> timeout(long timeout, TimeUnit unit, Scheduler scheduler) {
         return timeout0(timeout, unit, scheduler, null);
@@ -2749,6 +2853,7 @@ public final Single<T> timeout(long timeout, TimeUnit unit, Scheduler scheduler)
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     public final Single<T> timeout(long timeout, TimeUnit unit, Scheduler scheduler, SingleSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -2769,6 +2874,7 @@ public final Single<T> timeout(long timeout, TimeUnit unit, Scheduler scheduler,
      * @return the new Single instance
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     public final Single<T> timeout(long timeout, TimeUnit unit, SingleSource<? extends T> other) {
         ObjectHelper.requireNonNull(other, "other is null");
@@ -2794,6 +2900,7 @@ private Single<T> timeout0(final long timeout, final TimeUnit unit, final Schedu
      *
      * @return the value returned by the convert function
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <R> R to(Function<? super Single<T>, R> convert) {
         try {
@@ -2822,6 +2929,7 @@ public final <R> R to(Function<? super Single<T>, R> convert) {
      * @see <a href="http://reactivex.io/documentation/completable.html">ReactiveX documentation: Completable</a>
      * @since 2.0
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Completable toCompletable() {
         return RxJavaPlugins.onAssembly(new CompletableFromSingle<T>(this));
@@ -2841,6 +2949,7 @@ public final Completable toCompletable() {
      * @return a {@link Flowable} that emits a single item T or an error.
      */
     @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public final Flowable<T> toFlowable() {
@@ -2862,6 +2971,7 @@ public final Flowable<T> toFlowable() {
      * @return a {@link Future} that expects a single item to be emitted by this {@code Single}
      * @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX documentation: To</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Future<T> toFuture() {
         return subscribeWith(new FutureSingleObserver<T>());
@@ -2878,6 +2988,7 @@ public final Future<T> toFuture() {
      *
      * @return a {@link Maybe} that emits a single item T or an error.
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public final Maybe<T> toMaybe() {
@@ -2897,6 +3008,7 @@ public final Maybe<T> toMaybe() {
      *
      * @return an {@link Observable} that emits a single item T or an error.
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     public final Observable<T> toObservable() {
@@ -2929,6 +3041,7 @@ public final Observable<T> toObservable() {
      *         and emits the results of {@code zipFunction} applied to these pairs
      * @see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>
      */
+    @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public final <U, R> Single<R> zipWith(SingleSource<U> other, BiFunction<? super T, ? super U, ? extends R> zipper) {
         return zip(this, other, zipper);
diff --git a/src/main/java/io/reactivex/annotations/CheckReturnValue.java b/src/main/java/io/reactivex/annotations/CheckReturnValue.java
index 0af6b90a78..ecb8f33776 100644
--- a/src/main/java/io/reactivex/annotations/CheckReturnValue.java
+++ b/src/main/java/io/reactivex/annotations/CheckReturnValue.java
@@ -21,7 +21,7 @@
 
 /**
  * Marks methods whose return values should be checked.
- * 
+ *
  * @since 2.0.2 - experimental
  */
 @Retention(RetentionPolicy.RUNTIME)
diff --git a/src/test/java/io/reactivex/BaseTypeAnnotations.java b/src/test/java/io/reactivex/BaseTypeAnnotations.java
index 3e9c3501a6..ad0b18e2d1 100644
--- a/src/test/java/io/reactivex/BaseTypeAnnotations.java
+++ b/src/test/java/io/reactivex/BaseTypeAnnotations.java
@@ -15,7 +15,7 @@
 
 import static org.junit.Assert.fail;
 
-import java.lang.reflect.Method;
+import java.lang.reflect.*;
 
 import org.junit.Test;
 import org.reactivestreams.Publisher;
@@ -25,6 +25,7 @@
 /**
  * Verifies several properties.
  * <ul>
+ * <li>Certain public base type methods have the {@link CheckReturnValue} present</li>
  * <li>All public base type methods have the {@link SchedulerSupport} present</li>
  * <li>All public base type methods which return Flowable have the {@link BackpressureSupport} present</li>
  * <li>All public base types that don't return Flowable don't have the {@link BackpressureSupport} present (these are copy-paste errors)</li>
@@ -32,6 +33,51 @@
  */
 public class BaseTypeAnnotations {
 
+    static void checkCheckReturnValueSupport(Class<?> clazz) {
+        StringBuilder b = new StringBuilder();
+
+        for (Method m : clazz.getMethods()) {
+            if (m.getName().equals("bufferSize")) {
+                continue;
+            }
+            if (m.getDeclaringClass() == clazz) {
+                boolean isSubscribeMethod = "subscribe".equals(m.getName()) && m.getParameterCount() == 0;
+                boolean isAnnotationPresent = m.isAnnotationPresent(CheckReturnValue.class);
+
+                if (isSubscribeMethod) {
+                    if (isAnnotationPresent) {
+                        b.append("subscribe() method has @CheckReturnValue: ").append(m).append("\r\n");
+                    }
+                    continue;
+                }
+
+                if (Modifier.isPrivate(m.getModifiers()) && isAnnotationPresent) {
+                    b.append("Private method has @CheckReturnValue: ").append(m).append("\r\n");
+                    continue;
+                }
+
+                if (m.getReturnType().equals(Void.TYPE)) {
+                    if (isAnnotationPresent) {
+                        b.append("Void method has @CheckReturnValue: ").append(m).append("\r\n");
+                    }
+                    continue;
+                }
+
+                if (!isAnnotationPresent) {
+                    b.append("Missing @CheckReturnValue: ").append(m).append("\r\n");
+                }
+            }
+        }
+
+        if (b.length() != 0) {
+            System.out.println(clazz);
+            System.out.println("------------------------");
+            System.out.println(b);
+
+            fail(b.toString());
+        }
+    }
+
     static void checkSchedulerSupport(Class<?> clazz) {
         StringBuilder b = new StringBuilder();
 
@@ -128,6 +174,31 @@ static void checkBackpressureSupport(Class<?> clazz) {
         }
     }
 
+    @Test
+    public void checkReturnValueFlowable() {
+        checkCheckReturnValueSupport(Flowable.class);
+    }
+
+    @Test
+    public void checkReturnValueObservable() {
+        checkCheckReturnValueSupport(Observable.class);
+    }
+
+    @Test
+    public void checkReturnValueSingle() {
+        checkCheckReturnValueSupport(Single.class);
+    }
+
+    @Test
+    public void checkReturnValueCompletable() {
+        checkCheckReturnValueSupport(Completable.class);
+    }
+
+    @Test
+    public void checkReturnValueMaybe() {
+        checkCheckReturnValueSupport(Maybe.class);
+    }
+
     @Test
     public void schedulerSupportFlowable() {
         checkSchedulerSupport(Flowable.class);

From 94571e5e30180ebcf337e01540d2b5f5f0c639c7 Mon Sep 17 00:00:00 2001
From: Niklas Baudy <niklas.baudy@vanniktech.de>
Date: Thu, 24 Nov 2016 15:38:21 +0100
Subject: [PATCH 3/3] Java 6 Compatibility

---
 src/test/java/io/reactivex/BaseTypeAnnotations.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/java/io/reactivex/BaseTypeAnnotations.java b/src/test/java/io/reactivex/BaseTypeAnnotations.java
index ad0b18e2d1..716c90616e 100644
--- a/src/test/java/io/reactivex/BaseTypeAnnotations.java
+++ b/src/test/java/io/reactivex/BaseTypeAnnotations.java
@@ -41,7 +41,7 @@ static void checkCheckReturnValueSupport(Class<?> clazz) {
                 continue;
             }
             if (m.getDeclaringClass() == clazz) {
-                boolean isSubscribeMethod = "subscribe".equals(m.getName()) && m.getParameterCount() == 0;
+                boolean isSubscribeMethod = "subscribe".equals(m.getName()) && m.getParameterTypes().length == 0;
                 boolean isAnnotationPresent = m.isAnnotationPresent(CheckReturnValue.class);
 
                 if (isSubscribeMethod) {