Update fields of the principal at the runtime - spring

Question

I use OAuth2 authentication with my own authorization and resource server in Spring Boot. I want to change some fields in my User implements UserDetails(it's my Principal) object at runtime on behalf of the same user or on behalf of another user(administrator/moderator). E.g. user1 with id=1 want to change his country, so he calls this method:
#PostMapping("/setMyCountry")
public void setMyCountry(#CurrentUser User user, #RequestParam String newCountry){
user.setCountry(newCountry);
userRepository.save(user);
}
But when I want to check his country using this:
#GetMapping("/getMyCountry")
public String getMyCountry(#CurrentUser User user){
return user.getCountry();
}
I get the same old country.
Similarly, with the changes as administrator:
#PostMapping("/setUserCountry")
public void setUserCountry(#CurrentUser Moderator moderator, #RequestParam String newCountry){
User user = userRepository.findById(1L).get();
user.setCountry(newCountry);
userRepository.save(user);
}
#GetMapping("/getUserCountry")
public String getUserCountry(#CurrentUser Moderator moderator){
User user = userRepository.findById(1L).get();
return user.getCountry();
}
It returns the same country. But, of course, the DB shows new value.
I already saw question about the similar issues, but if I use this in setMyCountry():
Authentication newAuth = new UsernamePasswordAuthenticationToken(user, user.getPassword(), user.getAuthorities());
SecurityContextHolder.getContext().setAuthentication(newAuth);
then this still doesn't work. Please note, that I use my custom tokens, token providers and token granters, but they all return UsernamePasswordAuthenticationToken at the end.
So, how can I change field of the User and update current principal without log out and log in?

Answer 1

Common practice when using oauth2 is that the Authentication server knows nothing about the users, more than user name, password, what roles, and an some sort of key so it can look up the user object. This can be a unique UUID, or the username (subject) as in an email address.
The resource server gets a token from a client, it takes this token and then calls the authorization server to verify the token, the authorization server verifies it and if verified then sends back information to the resource server so that the resource server can populate its UserDetails object.
If the resource server needs to know say what country this user lives in, it gets the id from the Principal/UserDetails object and then calls maybe a user service, or another database, or another table, or even back to the authorization server that maybe has a /user endpoint and presents the token to the authorization server (that in turn gets the principal info, gets the subject and then looks up in a database for the user info) and then send the user object back.
What my point is that you should always separate Authentication and Authorization (roles etc) information, from the actual User information.
What if you change from say using facebook authentication to github authentication. Do you need to redo all the users? no, because you have all user information separated from the authorization information.