title: RxJava2, Retrofit - doOnNext, doAfterNext, doOnComplete doesn't call
body: <p>I try to get some data from server. </p>
  
  <pre><code>Observable&lt;List&lt;Countries&gt;&gt; backendObservable = mCountriesApi.getCountries()
              .subscribeOn(Schedulers.newThread())
              .observeOn(AndroidSchedulers.mainThread());
  
  backendObservable.doOnNext(list -&gt; Log.d(TAG, "doOnNext"));
  backendObservable.doAfterNext(list -&gt; Log.d(TAG, "doAfterNext"));
  backendObservable.doOnComplete(() -&gt; Log.d(TAG, "doOnComplete"));
  
  backendObservable.subscribe(new Observer&lt;List&lt;Country&gt;&gt;() {
          @Override
          public void onSubscribe(Disposable d) {
  
          }
  
          @Override
          public void onNext(List&lt;Country&gt; value) {
              Log.d(TAG, "doOnNext"));
          }
  
          @Override
          public void onError(Throwable e) {
  
          }
  
          @Override
          public void onComplete() {
  
          }
      });
  </code></pre>
  
  <p>It's works, I receive data into "onNext". But methods doOnNext, doAfterNext, doOnComplete doesn't call. 
  What i doing wrong ? </p>