*
   * @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 28.2
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submit(
      Callable<O> callable, Executor executor) {
    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    executor.execute(task);
    return task;
  }

  /**

    allTasks.add(setFutureCompleteExceptionallyRunnable);
    allTasks.add(setFutureCancelRunnable);
    for (int k = 0; k < 50; k++) {
      // For each listener we add a task that submits it to the executor directly for the blocking
      // get use case and another task that adds it as a listener to the future to exercise both
      // racing addListener calls and addListener calls completing after the future completes.
      final Runnable listener =

import javax.annotation.CheckForNull;

/**
 * {@link Error} variant of {@link java.util.concurrent.ExecutionException}. As with {@code
 * ExecutionException}, the error's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread. That cause should itself be an {@code Error}; if not, use {@code
 * ExecutionException} or {@link UncheckedExecutionException}. This allows the client code to

            directExecutor());

    // Wait for the first task to be started in the background. It will block until we explicitly
    // stop it.
    blockingCallable.waitForStart();

    // Give the second task a chance to (incorrectly) start up while the first task is running.
    assertThat(future2.isDone()).isFalse();

    // Stop the first task. The second task should then run.
    blockingCallable.stop();

            directExecutor());

    // Wait for the first task to be started in the background. It will block until we explicitly
    // stop it.
    blockingCallable.waitForStart();

    // Give the second task a chance to (incorrectly) start up while the first task is running.
    assertThat(future2.isDone()).isFalse();

    // Stop the first task. The second task should then run.
    blockingCallable.stop();

  }

  /**
   * Submits a blocking task for the given {@link Future} to provide {@link ListenableFuture}
   * functionality.
   *
   * <p><b>Warning:</b> If the input future does not already implement {@code ListenableFuture}, the
   * returned future will emulate {@link ListenableFuture#addListener} by submitting a task to the
   * given executor at the first call to {@code addListener}. The task must be started by the

                return callable.toString();
              }
            });
    executor.execute(task);
    this.future = task;
  }

  private ClosingFuture(final AsyncClosingCallable<V> callable, Executor executor) {
    checkNotNull(callable);
    TrustedListenableFutureTask<V> task =
        TrustedListenableFutureTask.create(
            new AsyncCallable<V>() {
              @Override

      assertFalse(Files.exists(symlink, NOFOLLOW_LINKS));
      assertTrue(Files.isDirectory(realSymlinkTarget, NOFOLLOW_LINKS));
    }
  }

  /**
   * Starts a new task on the given executor that switches (deletes and replaces) a file between
   * being a directory and being a symlink. The given {@code file} is the file that should switch

 * ExecutionException}, the exception's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread.
 *
 * <p>{@code UncheckedExecutionException} is intended as an alternative to {@code
 * ExecutionException} when the exception thrown by a task is an unchecked exception. However, it
 * may also wrap a checked exception in some cases.
 *

            new AsyncCallable<String>() {
              @Override
              public ListenableFuture<String> call() throws Exception {
                // Make this executor terminate after this task so that the test can tell when
                // futureResult has received resultOfCombiner.
                executor.shutdown();
                callableBlocking.await();
                return resultOfCombiner;