docs: @Override
      public UserRegistryService getUserRegistryService() {
          UserRegistryService service = userRegistryService.get();
          if (service == null) {
              if (isConfigurationDefinedInFile()) {
                  String id = getEffectiveSecurityConfiguration().getUserRegistryServiceId();
                  service = getUserRegistryService(id);
              } else {
                  service = autoDetectService(KEY_USERREGISTRY, userRegistry);
              }
              // remember the user registry
              userRegistryService.set(service);
          }
          return service;
      }