/**
 * Helper interface to implement both {@link ListenableFuture} and {@link ScheduledFuture}.
 *
 * @author Anthony Zana
 * @since 15.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface ListenableScheduledFuture<V extends @Nullable Object>

  private static class ImmediateScheduledFuture<V> extends SimpleForwardingListenableFuture<V>
      implements ListenableScheduledFuture<V> {
    static <V> ListenableScheduledFuture<V> of(V value) {
      return new ImmediateScheduledFuture<>(Futures.immediateFuture(value));
    }

    static <V> ListenableScheduledFuture<V> failed(Throwable t) {
      return new ImmediateScheduledFuture<>(Futures.immediateFailedFuture(t));
    }

  /** @since 15.0 (previously returned ScheduledFuture) */
  @Override
  ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit);

  /** @since 15.0 (previously returned ScheduledFuture) */
  @Override
  <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
      Callable<V> callable, long delay, TimeUnit unit);

  }

  @Override
  public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
    Preconditions.checkNotNull(command, "command must not be null");
    Preconditions.checkNotNull(unit, "unit must not be null!");
    return schedule(java.util.concurrent.Executors.callable(command), delay, unit);
  }

  @Override
  public <V> ListenableScheduledFuture<V> schedule(

  }

  @Override
  public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
    Preconditions.checkNotNull(command, "command must not be null");
    Preconditions.checkNotNull(unit, "unit must not be null!");
    return schedule(java.util.concurrent.Executors.callable(command), delay, unit);
  }

  @Override
  public <V> ListenableScheduledFuture<V> schedule(

    }

    @Override
    public void execute(Runnable runnable) {}

    @Override
    public <V> ListenableScheduledFuture<V> schedule(
        Callable<V> callable, long delay, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    @Override
    public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    }

    @Override
    public void execute(Runnable runnable) {}

    @Override
    public <V> ListenableScheduledFuture<V> schedule(
        Callable<V> callable, long delay, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    @Override
    public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    ScheduledListeningDecorator(ScheduledExecutorService delegate) {
      super(delegate);
      this.delegate = checkNotNull(delegate);
    }

    @Override
    public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
      TrustedListenableFutureTask<@Nullable Void> task =
          TrustedListenableFutureTask.create(command, null);

          // caught and forwarded to the service the task would stop executing but the service would
          // have no idea.
          // TODO(lukes): consider building everything in terms of ListenableScheduledFuture then
          // the AbstractService could monitor the future directly. Rescheduling is still hard...
          // but it would help with some of these lock ordering issues.
          scheduleFailure = e;

   * @since 23.0
   */
  @J2ktIncompatible
  @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  // TODO(cpovirk): Return ListenableScheduledFuture?
  public static <O extends @Nullable Object> ListenableFuture<O> scheduleAsync(
      AsyncCallable<O> callable,
      long delay,
      TimeUnit timeUnit,
      ScheduledExecutorService executorService) {