docs: public List<ModelServiceInstance> getAllInstances(){
          HttpResponse result = invoker.invoke("/service" , null, HttpMethod.GET);
  
          if (result.getHttpCode() != HTTP_OK) {
             throw new ServiceException(ErrorCode.REMOTE_DIRECTORY_SERVER_ERROR,
                      "HTTP Code is not OK, code=%s", result.getHttpCode());
          }
  
          List<ModelServiceInstance> allInstances = _deserialize(result.getRetBody(), new TypeReference<List<ModelServiceInstance>>(){});
          return allInstances;
      }