Firestore: change timestampsInSnapshots default to true.

BREAKING CHANGE: The `areTimestampsInSnapshotsEnabled()` setting is now enabled
by default so timestamp fields read from a `DocumentSnapshot` will be returned
as `Timestamp` objects instead of `Date`. Any code expecting to receive a
`Date` object must be updated.

google-cloud-clients/google-cloud-firestore/src/main/java/com/google/cloud/firestore/FirestoreImpl.java

@@ -85,34 +85,6 @@ class FirestoreImpl implements Firestore {
             + "Please explicitly set your Project ID in FirestoreOptions.");
     this.databasePath =
         ResourcePath.create(DatabaseRootName.of(options.getProjectId(), options.getDatabaseId()));
-
-    if (!options.areTimestampsInSnapshotsEnabled()) {
-      LOGGER.warning(
-          "The behavior for java.util.Date objects stored in Firestore is going to change "
-              + "AND YOUR APP MAY BREAK.\n"
-              + "To hide this warning and ensure your app does not break, you need to add "
-              + "the following code to your app before calling any other Cloud Firestore "
-              + "methods:\n"
-              + "\n"
-              + "FirestoreOptions options = \n"
-              + "  FirestoreOptions.newBuilder().setTimestampsInSnapshotsEnabled(true).build();\n"
-              + "Firestore firestore = options.getService();\n"
-              + "\n"
-              + "With this change, timestamps stored in Cloud Firestore will be read back as "
-              + "com.google.cloud.Timestamp objects instead of as system java.util.Date "
-              + "objects. So you will also need to update code expecting a java.util.Date to "
-              + "instead expect a Timestamp. For example:\n"
-              + "\n"
-              + "// Old:\n"
-              + "java.util.Date date = (java.util.Date) snapshot.get(\"created_at\");\n"
-              + "// New:\n"
-              + "Timestamp timestamp = (Timestamp) snapshot.get(\"created_at\");\n"
-              + "java.util.Date date = timestamp.toDate();\n"
-              + "\n"
-              + "Please audit all existing usages of java.util.Date when you enable the new "
-              + "behavior. In a future release, the behavior will be changed to the new "
-              + "behavior, so if you do not follow these steps, YOUR APP MAY BREAK.");
-    }
   }
 
   /** Creates a pseudo-random 20-character ID that can be used for Firestore documents. */

google-cloud-clients/google-cloud-firestore/src/main/java/com/google/cloud/firestore/FirestoreOptions.java

@@ -44,7 +44,7 @@ public final class FirestoreOptions extends ServiceOptions<Firestore, FirestoreO
           .add("https://www.googleapis.com/auth/cloud-platform")
           .add("https://www.googleapis.com/auth/datastore")
           .build();
-  private static final boolean DEFAULT_TIMESTAMPS_IN_SNAPSHOTS_ENABLED = false;
+  private static final boolean DEFAULT_TIMESTAMPS_IN_SNAPSHOTS_ENABLED = true;
 
   private static final long serialVersionUID = -5853552236134770090L;
 
@@ -179,26 +179,26 @@ public Builder setDatabaseId(@Nonnull String databaseId) {
     }
 
     /**
-     * Enables the use of {@link com.google.cloud.Timestamp Timestamps} for timestamp fields in
-     * {@link DocumentSnapshot DocumentSnapshots}.
+     * Specifies whether to use {@link com.google.cloud.Timestamp Timestamps} for timestamp fields
+     * in {@link DocumentSnapshot DocumentSnapshots}. This is now enabled by default and should not
+     * be disabled.
      *
-     * <p>Currently, Firestore returns timestamp fields as {@link java.util.Date} but {@link
-     * java.util.Date Date} only supports millisecond precision, which leads to truncation and
-     * causes unexpected behavior when using a timestamp from a snapshot as a part of a subsequent
-     * query.
+     * <p>Previously, Firestore returned timestamp fields as {@link java.util.Date} but {@link
+     * java.util.Date} only supports millisecond precision, which leads to truncation and causes
+     * unexpected behavior when using a timestamp from a snapshot as a part of a subsequent query.
      *
-     * <p>Setting {@code setTimestampsInSnapshotsEnabled(true)} will cause Firestore to return
-     * {@link com.google.cloud.Timestamp Timestamp} values instead of {@link java.util.Date Date},
-     * avoiding this kind of problem. To make this work you must also change any code that uses
-     * {@link java.util.Date Date} to use {@link com.google.cloud.Timestamp Timestamp} instead.
+     * <p>So now Firestore returns {@link com.google.cloud.Timestamp Timestamp} values instead of
+     * {@link java.util.Date}, avoiding this kind of problem.
      *
-     * <p>NOTE: in the future {@link FirestoreOptions#areTimestampsInSnapshotsEnabled} will default
-     * to true and this option will be removed so you should change your code to use Timestamp now
-     * and opt-in to this new behavior as soon as you can.
+     * <p>To opt into the old behavior of returning {@link java.util.Date Dates}, you can
+     * temporarily set {@link FirestoreOptions#areTimestampsInSnapshotsEnabled} to false.
      *
-     * @return A settings object on which the return type for timestamp fields is configured as
-     *     specified by the given {@code value}.
+     * @deprecated This setting now defaults to true and will be removed in a future release. If you
+     *     are already setting it to true, just remove the setting. If you are setting it to false,
+     *     you should update your code to expect {@link com.google.cloud.Timestamp Timestamps}
+     *     instead of {@link java.util.Date Dates} and then remove the setting.
      */
+    @Deprecated
     @Nonnull
     public Builder setTimestampsInSnapshotsEnabled(boolean value) {
       this.timestampsInSnapshotsEnabled = value;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/CollectionReferenceTest.java

@@ -43,10 +43,7 @@ public class CollectionReferenceTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
           Mockito.mock(FirestoreRpc.class));
 
   @Captor private ArgumentCaptor<CommitRequest> argCaptor;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/ConformanceTest.java

@@ -133,11 +133,7 @@ public ConformanceTest() {
     firestoreMock =
         Mockito.spy(
             new FirestoreImpl(
-                FirestoreOptions.newBuilder()
-                    .setProjectId("projectID")
-                    .setTimestampsInSnapshotsEnabled(true)
-                    .build(),
-                firestoreRpc));
+                FirestoreOptions.newBuilder().setProjectId("projectID").build(), firestoreRpc));
     watchQuery = collection("projects/projectID/databases/(default)/documents/C").orderBy("a");
   }
 

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/DocumentReferenceTest.java

@@ -94,10 +94,7 @@ public class DocumentReferenceTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
           Mockito.mock(FirestoreRpc.class));
 
   @Captor private ArgumentCaptor<CommitRequest> commitCapture;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/FirestoreTest.java

@@ -44,10 +44,7 @@ public class FirestoreTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
           Mockito.mock(FirestoreRpc.class));
 
   @Captor private ArgumentCaptor<BatchGetDocumentsRequest> getAllCapture;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/QueryTest.java

@@ -61,10 +61,7 @@ public class QueryTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
           Mockito.mock(FirestoreRpc.class));
 
   @Captor private ArgumentCaptor<RunQueryRequest> runQuery;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/TransactionTest.java

@@ -77,11 +77,7 @@ public class TransactionTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
-          firestoreRpc);
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(), firestoreRpc);
 
   @Captor private ArgumentCaptor<Message> requestCapture;
   @Captor private ArgumentCaptor<ApiStreamObserver<Message>> streamObserverCapture;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/WatchTest.java

@@ -97,11 +97,7 @@ public class WatchTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
-          firestoreRpc);
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(), firestoreRpc);
 
   @Captor private ArgumentCaptor<ApiStreamObserver<ListenResponse>> streamObserverCapture;
 

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/WriteBatchTest.java

@@ -52,10 +52,7 @@ public class WriteBatchTest {
   @Spy
   private FirestoreImpl firestoreMock =
       new FirestoreImpl(
-          FirestoreOptions.newBuilder()
-              .setProjectId("test-project")
-              .setTimestampsInSnapshotsEnabled(true)
-              .build(),
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
           Mockito.mock(FirestoreRpc.class));
 
   @Captor private ArgumentCaptor<CommitRequest> commitCapture;

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/it/ITSystemTest.java

@@ -86,8 +86,7 @@ public class ITSystemTest {
 
   @Before
   public void before() {
-    FirestoreOptions firestoreOptions =
-        FirestoreOptions.newBuilder().setTimestampsInSnapshotsEnabled(true).build();
+    FirestoreOptions firestoreOptions = FirestoreOptions.newBuilder().build();
     firestore = firestoreOptions.getService();
     randomColl =
         firestore.collection(