}

    @Nested
    class UserDomainTests {
        @Test
        @DisplayName("getUserDomain: derives from KerberosPrincipal in Subject")
        void getUserDomain_fromSubjectPrincipal() {
            Subject subject = new Subject();
            Principal kp = new KerberosPrincipal("******@****.***");
            subject.getPrincipals().add(kp);

            Kerb5Authenticator auth = new Kerb5Authenticator(subject);

            Set<Principal> pr = this.getSubject().getPrincipals();
            for (Iterator<Principal> ite = pr.iterator(); ite.hasNext();) {
                try {
                    KerberosPrincipal entry = (KerberosPrincipal) ite.next();
                    return entry.getRealm();
                } catch (Exception e) {
                    continue;
                }
            }
        }