docs: @Override
      public ServiceInstance lookupInstance(String serviceName)
              throws ServiceException {
          if(! isStarted){
              ServiceDirectoryError error = new ServiceDirectoryError(ErrorCode.SERVICE_DIRECTORY_MANAGER_FACTORY_CLOSED);
              throw new ServiceException(error);
          }
  
          ServiceRRLoadBalancer lb = lbManager.getServiceRRLoadBalancer(serviceName);
          return lb.vote();
      }