* executor to the given {@code future}.
   *
   * <p>Note, the returned executor can only be used once.
   */
  static Executor rejectionPropagatingExecutor(Executor delegate, AbstractFuture<?> future) {
    checkNotNull(delegate);
    checkNotNull(future);
    if (delegate == directExecutor()) {
      // directExecutor() cannot throw RejectedExecutionException