References
https://github.com/fdlessard/SpringBootOAuth2Message
https://docs.spring.io/spring-security/site/docs/current/reference/html5/
https://www.baeldung.com/spring-security-5-oauth2-login#setup https://www.baeldung.com/spring-webclient-oauth2
https://github.com/spring-projects/spring-security/wiki/OAuth-2.0-Features-Matrix
https://github.com/rwinch/webclientoauth2-cli https://github.com/Brico87/spring-security-oauth2-m2m