? (ListeningScheduledExecutorService) delegate
        : new ScheduledListeningDecorator(delegate);
  }

  @GwtIncompatible // TODO
  private static class ListeningDecorator extends AbstractListeningExecutorService {
    private final ExecutorService delegate;

    ListeningDecorator(ExecutorService delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override