I am building a spring boot java resource server as a backend for an iOS app. The iOS App authenticates users using federated login with Facebook and passes access token for resource server to create an internal user. linked to the facebook profile.
Any documentation I came across discusses how to use spring security to authenticate/authorize users using login form, but I am just trying to parse/validate the access token already given by FB. How can I do this? Google offers a library to easily parse access token and extract user's information, but I can't find a counterpart library for facebook.