void getUserDomain_fromSubjectPrincipal() {
            Subject subject = new Subject();
            Principal kp = new KerberosPrincipal("******@****.***");
            subject.getPrincipals().add(kp);

            Kerb5Authenticator auth = new Kerb5Authenticator(subject);
            assertEquals("EXAMPLE.COM", auth.getUserDomain());
        }

        @Test

com.gl
com.gn
com.gp
com.gr
com.gt
com.gu
com.gy
com.hk
com.hn
com.hr
com.ht
com.im
com.in
com.io
com.iq
com.jo
com.kg
com.ki
com.km
com.kp
com.kw
com.ky
com.kz
com.la
com.lb
com.lc
com.lk
com.lr
com.lv
com.ly
com.mg
com.mk
com.ml
com.mo
com.ms
com.mt
com.mu
com.mv
com.mw