code: public <T> void restartableFirst(int restartableId, final Func0<Observable<T>> observableFactory, final Action2<View, T> onNext) {
          restartableFirst(restartableId, observableFactory, onNext, null);
      }
docs: This is a shortcut for calling {@link #restartableFirst(int, Func0, Action2, Action2)} with the last parameter = null.