Fix FutureIml tryComplete.

When complete error is regarded as a normal result, the Listener's complete result is inconsistent

src/main/java/io/vertx/core/impl/future/FutureImpl.java

@@ -50,28 +50,28 @@ class FutureImpl<T> extends FutureBase<T> {
    * The result of the operation. This will be null if the operation failed.
    */
   public synchronized T result() {
-    return value instanceof Throwable ? null : value == NULL_VALUE ? null : (T) value;
+    return value instanceof CauseHolder ? null : value == NULL_VALUE ? null : (T) value;
   }
 
   /**
    * An exception describing failure. This will be null if the operation succeeded.
    */
   public synchronized Throwable cause() {
-    return value instanceof Throwable ? (Throwable) value : null;
+    return value instanceof CauseHolder ? ((CauseHolder)value).cause : null;
   }
 
   /**
    * Did it succeed?
    */
   public synchronized boolean succeeded() {
-    return value != null && !(value instanceof Throwable);
+    return value != null && !(value instanceof CauseHolder);
   }
 
   /**
    * Did it fail?
    */
   public synchronized boolean failed() {
-    return value instanceof Throwable;
+    return value instanceof CauseHolder;
   }
 
   /**
@@ -155,8 +155,8 @@ public void addListener(Listener<T> listener) {
         return;
       }
     }
-    if (v instanceof Throwable) {
-      emitFailure((Throwable) v, listener);
+    if (v instanceof CauseHolder) {
+      emitFailure(((CauseHolder)v).cause, listener);
     } else {
       if (v == NULL_VALUE) {
         v = null;
@@ -190,7 +190,7 @@ public boolean tryFail(Throwable cause) {
       if (value != null) {
         return false;
       }
-      value = cause;
+      value = new CauseHolder(cause);
       l = listener;
       listener = null;
     }
@@ -203,8 +203,8 @@ public boolean tryFail(Throwable cause) {
   @Override
   public String toString() {
     synchronized (this) {
-      if (value instanceof Throwable) {
-        return "Future{cause=" + ((Throwable)value).getMessage() + "}";
+      if (value instanceof CauseHolder) {
+        return "Future{cause=" + ((CauseHolder)value).cause.getMessage() + "}";
       }
       if (value != null) {
         if (value == NULL_VALUE) {
@@ -237,4 +237,13 @@ public void onFailure(Throwable failure) {
       }
     }
   }
+
+  private static class CauseHolder {
+
+    private final Throwable cause;
+
+    CauseHolder(Throwable cause) {
+      this.cause = cause;
+    }
+  }
 }

src/test/java/io/vertx/core/FutureTest.java

@@ -209,6 +209,21 @@ public void testFailureFutureWithNullFailure() {
     assertNull(failure.getMessage());
   }
 
+  @Test
+  public void testCompleteCause() {
+    Throwable object = new RuntimeException();
+    Promise<Throwable> promise = Promise.promise();
+    AtomicReference<Boolean> r1 = new AtomicReference<>();
+    AtomicReference<Boolean> r2 = new AtomicReference<>();
+    promise.future().onSuccess(v -> r1.set(true)).onFailure(v -> r1.set(false));
+    Checker<Throwable>  checker = new Checker<>(promise.future());
+    promise.complete(object);
+    checker.assertSucceeded(object);
+    promise.future().onSuccess(v -> r2.set(true)).onFailure(v -> r2.set(false));
+    assertTrue(r1.get());
+    assertTrue(r2.get());
+  }
+
   @Test
   public void testComposeSuccessToSuccess() {
     AtomicReference<String> ref = new AtomicReference<>();