This is a backward compatible change, it just adds options for an authentication bundle that wants to modify the session.

An AuthenticationService is asked to return a value of type Authenticated. If the Authenticated also implements the com.openexchange.authentication.SessionEnhancement interface, it will receive a callback with the session constructed in SessionD. The bundle can then, in a typical case, set certain parameters via Session#setParameter(String,Object) and in a different custom bundle query them again.