message: remove custom sign in resolver
diff: @@ -189,79 +189,7 @@ components: {
  },
  ```
  -### Add sign-in resolver in the backend
  -
  -The Auth backend plugin is responsible for assigning a [Backstage User Identity](../auth/identity-resolver.md#backstage-user-identity) when a user signs in. The Backstage User Identity is fundamentally a JSON Web Token which consists of two parts. The `sub` part is your identity and that identifies your user for any purpose within the Backstage ecosystem. It can for example be used as a primary key in a per-user settings backend, or any other similar purpose. The ent is what relates to ownership (the list of entity refs through which you claim ownership). This is achieved by writing a [Sign In Resolver](../auth/identity-resolver.md#sign-in-resolvers) which takes care of assigning the right identity to the user and even reject SignIn attempts from unrecognized email domains.
  -
  -> Since [v1.1.0](https://github.com/backstage/backstage/releases/tag/v1.1.0-next.3), you must provide an [explicit sign-in resolver](../auth/identity-resolver.md).
  -
  -For now, let's create a simple Sign In Resolver which uses the first part of the user's email address to assign a Backstage User Identity.
  -
  -Replace your `packages/backend/src/plugin/auth.ts` file with the following.
  -
  -> NOTE: Please update `acme.org` below with your actual company domain to allow login requests from email address with that domain.
  -
  -```tsx
  -import {
  - createRouter,
  - providers,
  - defaultAuthProviderFactories,
  -} from '@backstage/plugin-auth-backend';
  -import { Router } from 'express';
  -import { PluginEnvironment } from '../types';
  -import {
  - DEFAULT_NAMESPACE,
  - stringifyEntityRef,
  -} from '@backstage/catalog-model';
  -
  -export default async function createPlugin(
  - env: PluginEnvironment,
  -): Promise<Router> {
  - return await createRouter({
  - logger: env.logger,
  - config: env.config,
  - database: env.database,
  - discovery: env.discovery,
  - tokenManager: env.tokenManager,
  - providerFactories: {
  - ...defaultAuthProviderFactories,
  - github: providers.github.create({
  - signIn: {
  - resolver: async ({ profile }, ctx) => {
  - if (!profile.email) {
  - throw new Error(
  - 'Login failed, user profile does not contain an email',
  - );
  - }
  - // Split the email into the local part and the domain.
  - const [localPart, domain] = profile.email.split('@');
  -
  - // Next we verify the email domain. It is recommended to include this
  - // kind of check if you don't look up the user in an external service.
  - if (domain !== 'acme.org') {
  - throw new Error('Login failed, user email domain check failed');
  - }
  -
  - // By using `stringifyEntityRef` we ensure that the reference is formatted correctly
  - const userEntityRef = stringifyEntityRef({
  - kind: 'User',
  - name: localPart,
  - namespace: DEFAULT_NAMESPACE,
  - });
  -
  - return ctx.issueToken({
  - claims: {
  - sub: userEntityRef,
  - ent: [userEntityRef],
  - },
  - });
  - },
  - },
  - }),
  - },
  - });
  -}
  -```
  +> Note: The default Backstage app comes with a guest Sign In Resolver. This resolver makes all users share a single "guest" identity and is only intended as a minimum requirement to quickly get up and running. You can read more about how [Sign In Resolvers](../auth/identity-resolver.md#sign-in-resolvers) play a role in creating a [Backstage User Identity](../auth/identity-resolver.md#backstage-user-identity) for logged in users.
  Restart Backstage from the terminal, by stopping it with `Control-C`, and starting it with `yarn dev` . You should be welcomed by a login prompt!
  