code: public final Flux<T> doOnNext(Consumer<? super T> onNext) {
  		Objects.requireNonNull(onNext, "onNext");
  		return doOnSignal(this, null, onNext, null, null, null, null, null);
  	}
docs: Add behavior (side-effect) triggered when the {@link Flux} emits an item.
  <p>
  <img class="marble" src="doc-files/marbles/doOnNextForFlux.svg" alt="">
  
  @param onNext the callback to call on {@link Subscriber#onNext}
  
  @reactor.errorMode This operator supports {@link #onErrorContinue(BiConsumer) resuming on errors}
  (including when fusion is enabled). Exceptions thrown by the consumer are passed to
  the {@link #onErrorContinue(BiConsumer)} error consumer (the value consumer
  is not invoked, as the source element will be part of the sequence). The onNext
  signal is then propagated as normal.
  
  @return an observed  {@link Flux}