docs: public Observable<List<EntityExtractor>> listCustomPrebuiltEntitiesAsync(UUID appId, String versionId) {
          return listCustomPrebuiltEntitiesWithServiceResponseAsync(appId, versionId).map(new Func1<ServiceResponse<List<EntityExtractor>>, List<EntityExtractor>>() {
              @Override
              public List<EntityExtractor> call(ServiceResponse<List<EntityExtractor>> response) {
                  return response.body();
              }
          });
      }