abstract void setResult(@ParametricNullness T result);

  @Override
  protected final void afterDone() {
    @RetainedLocalRef ListenableFuture<? extends V> localInputFuture = inputFuture;
    maybePropagateCancellationTo(localInputFuture);
    this.inputFuture = null;
    this.exceptionType = null;
    this.fallback = null;
  }

  @Override
  protected @Nullable String pendingToString() {

      }
      return message;
    }
    return null;
  }

  @Override
  protected void afterDone() {
    @RetainedLocalRef ListenableFuture<? extends V> delegate = delegateRef;
    maybePropagateCancellationTo(delegate);

    @RetainedLocalRef Future<?> localTimer = timer;
    // Try to cancel the timer as an optimization.
    // timer may be null if this call to run was by the timer task since there is no happens-before

  abstract void setResult(@ParametricNullness T result);

  @Override
  protected final void afterDone() {
    @RetainedLocalRef ListenableFuture<? extends I> localInputFuture = inputFuture;
    maybePropagateCancellationTo(localInputFuture);
    this.inputFuture = null;
    this.function = null;
  }

  @Override
  protected @Nullable String pendingToString() {

   * the given future (if available).
   */
  @SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
  final void maybePropagateCancellationTo(@Nullable Future<?> related) {
    if (related != null & isCancelled()) {
      related.cancel(wasInterrupted());
    }
  }

  /**