code: @CheckReturnValue
      @SchedulerSupport(SchedulerSupport.NONE)
      public final Maybe<T> onErrorReturnItem(final T item) {
          ObjectHelper.requireNonNull(item, "item is null");
          return onErrorReturn(Functions.justFunction(item));
      }
docs: Instructs a Maybe to emit an item (returned by a specified function) rather than invoking
  {@link MaybeObserver#onError onError} if it encounters an error.
  <p>
  <img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/onErrorReturn.png" alt="">
  <p>
  You can use this to prevent errors from propagating or to supply fallback data should errors be
  encountered.
  <dl>
  <dt><b>Scheduler:</b></dt>
  <dd>{@code onErrorReturnItem} does not operate by default on a particular {@link Scheduler}.</dd>
  </dl>
  
  @param item
  the value that is emitted as onSuccess in case this Maybe signals an onError
  @return the new Maybe instance
  @see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>