code: public static <T> Mono<T> justOrEmpty(@Nullable Optional<? extends T> data) {
  		return data != null && data.isPresent() ? just(data.get()) : empty();
  	}
docs: Create a new {@link Mono} that emits the specified item if {@link Optional#isPresent()} otherwise only emits
  onComplete.
  
  <p>
  <img class="marble" src="doc-files/marbles/justOrEmpty.svg" alt="">
  <p>
  @param data the {@link Optional} item to onNext or onComplete if not present
  @param <T> the type of the produced item
  
  @return a {@link Mono}.