verify(config, times(1)).isAllowNTLMFallback();
        verify(config, times(1)).isUseRawNTLM();
    }

    @Test
    @DisplayName("refresh: throws unsupported operation")
    void refresh_throwsUnsupported() {
        Kerb5Authenticator auth = new Kerb5Authenticator((Subject) null);
        SmbUnsupportedOperationException ex = assertThrows(SmbUnsupportedOperationException.class, auth::refresh);