code: public final Mono<T> onErrorReturn(Predicate<? super Throwable> predicate, T fallbackValue) {
  		return onErrorResume(predicate,  throwable -> just(fallbackValue));
  	}
docs: Simply emit a captured fallback value when an error matching the given predicate is
  observed on this {@link Mono}.
  <p>
  <img class="marble" src="doc-files/marbles/onErrorReturnForMono.svg" alt="">
  
  @param predicate the error predicate to match
  @param fallbackValue the value to emit if an error occurs that matches the predicate
  
  @return a new {@link Mono}