*
   * @since 18.0 (present as MoreExecutors.sameThreadExecutor() since 10.0)
   */
  @GwtIncompatible // TODO
  public static ListeningExecutorService newDirectExecutorService() {
    return new DirectExecutorService();
  }

  /**
   * Returns an {@link Executor} that runs each task in the thread that invokes {@link
   * Executor#execute execute}, as in {@link CallerRunsPolicy}.
   *