docs: public Observable<StorageAccountListKeysResultInner> regenerateKeyAsync(String resourceGroupName, String accountName, String keyName) {
          return regenerateKeyWithServiceResponseAsync(resourceGroupName, accountName, keyName).map(new Func1<ServiceResponse<StorageAccountListKeysResultInner>, StorageAccountListKeysResultInner>() {
              @Override
              public StorageAccountListKeysResultInner call(ServiceResponse<StorageAccountListKeysResultInner> response) {
                  return response.body();
              }
          });
      }