code: private AuthorizationService getAuthorizationService(String id) {
          AuthorizationService service = authorization.getService(id);
          if (service == null) {
              throwIllegalArgumentExceptionInvalidAttributeValue(SecurityConfiguration.CFG_KEY_AUTHORIZATION_REF, id);
          }
          return service;
      }
docs: Retrieve the AuthorizationService for the specified id.
  
  @param id AuthorizationService id to retrieve
  @return A non-null AuthorizationService instance.