The JdbcUserDetailsManager class supports the ability to add a level of indirection between the users and the GrantedAuthority declarations by grouping GrantedAuthority into logical sets called groups.
Users are then assigned one or more groups, and their membership confers a set of the GrantedAuthority declarations:
As you can see in the preceding diagram, this indirection allows the assignment of the same set of roles to multiple users, by simply assigning any new users to existing groups. This is different behavior that we've seen so far, where previously we assigned GrantedAuthority directly to individual users. ...
