}
  }

  @GwtIncompatible // TODO
  private static final class ScheduledListeningDecorator extends ListeningDecorator
      implements ListeningScheduledExecutorService {
    @SuppressWarnings("hiding")
    final ScheduledExecutorService delegate;

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