You will find a version of this application in the source code in Github which has a whitelabel HTML interface and HTTP Basic authentication.
This one has a pretty login page and user approval page implemented similarly to the way we did the login page in the single server sample.
It also uses JWT to encode the tokens, so instead of using the "/user" endpoint, the resource server can pull enough information out of the token itself to do a simple authentication.
This code copy from null client in OAuth2 Multi-Factor Authentication