code: public static Task<Void> delay(long delay, CancellationToken cancellationToken) {
      return delay(delay, BoltsExecutors.scheduled(), cancellationToken);
    }
docs: Creates a task that completes after a time delay.
  
  @param delay The number of milliseconds to wait before completing the returned task. Zero and
  negative values are treated as requests for immediate execution.
  @param cancellationToken The optional cancellation token that will be checked prior to
  completing the returned task.