docs: public Observable<HierarchicalChildEntity> getHierarchicalEntityChildAsync(UUID appId, String versionId, UUID hEntityId, UUID hChildId) {
          return getHierarchicalEntityChildWithServiceResponseAsync(appId, versionId, hEntityId, hChildId).map(new Func1<ServiceResponse<HierarchicalChildEntity>, HierarchicalChildEntity>() {
              @Override
              public HierarchicalChildEntity call(ServiceResponse<HierarchicalChildEntity> response) {
                  return response.body();
              }
          });
      }