code: public final ParallelFlux<T> doOnComplete(Runnable onComplete) {
  		Objects.requireNonNull(onComplete, "onComplete");
  		return doOnSignal(this, null, null, null, onComplete, null, null, null, null);
  	}
docs: Run the specified runnable when a 'rail' completes.
  
  @param onComplete the callback
  
  @return the new {@link ParallelFlux} instance