docs: @Override
      public User getUser(String name) throws ServiceException {
          if(! isStarted){
              ServiceDirectoryError error = new ServiceDirectoryError(ErrorCode.SERVICE_DIRECTORY_MANAGER_FACTORY_CLOSED);
              throw new ServiceException(error);
          }
          if(name == null || name.isEmpty()){
              throw new IllegalArgumentException("The name can not be empty.");
          }
  
          return getRegistrationService().getUser(name);
      }