// TODO(cpovirk): Test forwarding more extensively.
  }

  public void testAddCallback() {
    FluentFuture<String> f = FluentFuture.from(immediateFuture("a"));
    boolean[] called = new boolean[1];
    f.addCallback(
        new FutureCallback<String>() {
          @Override
          public void onSuccess(String result) {
            called[0] = true;
          }

          @Override

   * @param executor The executor to run {@code callback} when the future completes.
   */
  public final void addCallback(FutureCallback<? super V> callback, Executor executor) {
    Futures.addCallback(this, callback, executor);
  }

   * @since 10.0
   */
  public static <V extends @Nullable Object> void addCallback(
      ListenableFuture<V> future, FutureCallback<? super V> callback, Executor executor) {
    Preconditions.checkNotNull(callback);
    future.addListener(new CallbackListener<V>(future, callback), executor);
  }

  /** See {@link #addCallback(ListenableFuture, FutureCallback, Executor)} for behavioral notes. */