docs: protected Map<String, Object> unsetUserRegistry(ServiceReference<UserRegistryService> ref) {
          userRegistry.removeReference((String) ref.getProperty(KEY_ID), ref);
          userRegistry.removeReference(String.valueOf(ref.getProperty(KEY_SERVICE_ID)), ref);
  
          // determine a new user registry service
          userRegistryService.set(null);
          return getServiceProperties();
      }