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