code: public Observable<Page<CognitiveServicesAccountInner>> listByResourceGroupAsync(String resourceGroupName) {
          return listByResourceGroupWithServiceResponseAsync(resourceGroupName).map(new Func1<ServiceResponse<List<CognitiveServicesAccountInner>>, Page<CognitiveServicesAccountInner>>() {
              @Override
              public Page<CognitiveServicesAccountInner> call(ServiceResponse<List<CognitiveServicesAccountInner>> response) {
                  PageImpl<CognitiveServicesAccountInner> page = new PageImpl<>();
                  page.setItems(response.body());
                  return page;
              }
          });
      }
docs: Returns all the resources of a particular type belonging to a resource group.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @return the observable to the List&lt;CognitiveServicesAccountInner&gt; object