void customOptions_arePropagated() {
        // Arrange
        Map<String, Object> opts = new HashMap<>();
        opts.put("useKeyTab", "true");
        opts.put("storeKey", "true");
        opts.put("principal", "******@****.***");
        StaticJAASConfiguration cfg = new StaticJAASConfiguration(opts);

        // Act
        AppConfigurationEntry[] entries = cfg.getAppConfigurationEntry("any");

        byte[] buffer = new byte[10];
        assertThrows(NullPointerException.class, () -> cmd.writeParametersWireFormat(buffer, 0));
    }

    @Nested
    @DisplayName("read methods are no‑ops")
    class ReadMethods {
        Trans2GetDfsReferral cmd = new Trans2GetDfsReferral("/foo");

        @Test
        void setup() {
            assertEquals(0, cmd.readSetupWireFormat(new byte[10], 0, 0));