code: public Observable<IotHubDescriptionInner> beginUpdateAsync(String resourceGroupName, String resourceName) {
          return beginUpdateWithServiceResponseAsync(resourceGroupName, resourceName).map(new Func1<ServiceResponse<IotHubDescriptionInner>, IotHubDescriptionInner>() {
              @Override
              public IotHubDescriptionInner call(ServiceResponse<IotHubDescriptionInner> response) {
                  return response.body();
              }
          });
      }
docs: Update an existing IoT Hubs tags.
  Update an existing IoT Hub tags. to update other fields use the CreateOrUpdate method.
  
  @param resourceGroupName Resource group identifier.
  @param resourceName Name of iot hub to update.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the IotHubDescriptionInner object