Spring Boot Rest service with oAuth2 Security credentials from database

Could anyone please help me with an example of a Spring Boot application that contains a Rest Service with endpoints protected by Spring Security using oAuth2 with user credentials from a MySQL database?

How does oauth2 work in REST API spring boot?

It works by delegating user authentication to the service that hosts the user account and authorizing third-party applications to access the user account. Oauth2 provides authorization flows for web and desktop applications, and mobile devices.

How about this one: https://github.com/spring-projects/spring-security-oauth/tree/master/tests/annotation/jdbc (it's not MySQL, but it's JDBC, so the transformation is trivial)?