WebLogic - Obtain Groups of an Autenticated User

Note for myself:

 for(Principal p: subject.getPrincipals()) {
            if(p instanceof WLSGroup) {
                if(first) {
                    first=false;
                } else {
                    groups.append(", ");
                }
                groups.append(p.getName());
            } else if (p instanceof WLSUser) {
                user = p.getName();
            }
        }