return delegate.submit(task);
  }

  @Override
  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
      throws InterruptedException {
    Preconditions.checkNotNull(tasks, "tasks must not be null!");
    return delegate.invokeAll(tasks);
  }

  @Override
  public <T> List<Future<T>> invokeAll(
      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)

  @Override
  AbstractFuture<@Nullable Integer> newDelegate() {
    AbstractFuture<@Nullable Integer> future = new TrustedFuture<@Nullable Integer>() {};
    assertTrue(future instanceof TrustedFuture); // sanity check
    return future;
  }

  @Override
  AbstractFuture<@Nullable Integer> newDelegate() {
    AbstractFuture<@Nullable Integer> future = new AbstractFuture<@Nullable Integer>() {};
    assertFalse(future instanceof TrustedFuture); // sanity check
    return future;
  }

  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/487687332
  public static void awaitDone(Future<?> future) {
    if (future.isDone()) {
      return;
    }

    Callable<String> callable = () -> expected;

    AsyncCallable<String> asyncCallable =
        Callables.asAsyncCallable(callable, newDirectExecutorService());

    ListenableFuture<String> future = asyncCallable.call();
    assertThat(future.get()).isEqualTo(expected);
  }

  @J2ktIncompatible
  @GwtIncompatible
  public void testAsAsyncCallable_exception() throws Exception {
    Exception expected = new IllegalArgumentException();

    Callable<String> callable = () -> expected;

    AsyncCallable<String> asyncCallable =
        Callables.asAsyncCallable(callable, newDirectExecutorService());

    ListenableFuture<String> future = asyncCallable.call();
    assertThat(future.get()).isEqualTo(expected);
  }

  @J2ktIncompatible
  @GwtIncompatible
  public void testAsAsyncCallable_exception() throws Exception {
    Exception expected = new IllegalArgumentException();

 * or method references instead of classes, leaving your code easier to migrate in the future.
 *
 * <p>To use an existing function (say, named {@code function}) in a context where the <i>other
 * type</i> of function is expected, use the method reference {@code function::apply}. A future
 * version of {@code com.google.common.base.Function} will be made to <i>extend</i> {@code

The [Hasher] interface type defines the contract between values of a
particular type and future hash-based data structures such as hash

 * the License.
 */

package com.google.common.util.concurrent.internal;


/**
 * A future that, if it fails, may <i>optionally</i> provide access to the cause of the failure.
 *
 * <p>This class is used only for micro-optimization. Standard {@code Future} utilities benefit from
 * this optimization, so there is no need to specialize methods to return or accept this type

    CountDownLatch latch = new CountDownLatch(1);
    SettableFuture<?> future = SettableFuture.create();
    Executor delegate =
        new Executor() {
          @Override
          public void execute(Runnable task) {
            if (future.set(null)) {
              awaitUninterruptibly(latch);
            }
            throw new RejectedExecutionException();