code: public Observable<Page<CognitiveServicesAccountInner>> listByResourceGroupNextAsync(final String nextPageLink) {
          return listByResourceGroupNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<CognitiveServicesAccountInner>>, Page<CognitiveServicesAccountInner>>() {
                  @Override
                  public Page<CognitiveServicesAccountInner> call(ServiceResponse<Page<CognitiveServicesAccountInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Returns all the resources of a particular type belonging to a resource group.
  
  @param nextPageLink The NextLink from the previous successful call to List operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;CognitiveServicesAccountInner&gt; object