d.setErrorCode(123); // non-zero error
        assertFalse(d.hasMoreElements(), "errorCode non-zero overrides hasMore flag");
    }

    @Test
    public void nextElement_firstCall_flipsIsPrimary() {
        DummyResponse d = new DummyResponse();
        // Initially isPrimary is true (inherited constructor)
        SmbComTransactionResponse r1 = (SmbComTransactionResponse) d.nextElement();