I have a working Spring REST API authenticated with OAuth2, and I consume this API from an Android app using the "password" grant_type, i.e. checking the username and password entered by the Android client against my DB.
Now I have the requirement of add the option of an alternative login using Facebook. I´ve managed to implement the Facebook login in the Android app until the step where I get from Facebook an UserID, and a Token (from an object called LoginResult).
My question is now what server side configuration changes I need to implement to obtain the access_token (and refresh_token, expires_in, etc) for my REST API from the (userID, token) values that I get in the app.
I've been looking for days, but I can´t find any example/tutorial/guide to get this done.
Many thanks in advance!!