code: public static <T> Observable<T> toObservable(final Publisher<T> publisher) {
          return Observable.create(new Observable.OnSubscribe<T>() {
              @Override
              public void call(final rx.Subscriber<? super T> rxSubscriber) {
                  publisher.subscribe(toSubscriber(rxSubscriber));
              }
          });
      }
docs: Convert a Reactive Streams {@link Publisher} into a Rx {@link Observable}.
  <p/>
  Use this method when you have a stream from another library, that you want to be consume as an RxJava observable.
  
  @param <T> the value type
  @param publisher the {@link Publisher} to convert.
  @return the converted {@link Observable}