message: use stringifyEntityRef to build the user reference
diff: @@ -109,6 +109,10 @@ import {
  createRouter,
  createAwsAlbProvider,
  } from '@backstage/plugin-auth-backend';
  +import {
  + DEFAULT_NAMESPACE,
  + stringifyEntityRef,
  +} from '@backstage/catalog-model';
  import { Router } from 'express';
  import { PluginEnvironment } from '../types';
  @@ -154,7 +158,7 @@ export default async function createPlugin({
  const [id] = email?.split('@') ?? '';
  // Fetch from an external system that returns entity claims like:
  // ['user:default/breanna.davison', ...]
  - const userEntityRef = `user:default/${id}`;
  + const userEntityRef = stringifyEntityRef({ kind: 'User', namespace: DEFAULT_NAMESPACE, name: id });
  // Resolve group membership from the Backstage catalog
  const fullEnt =
  