assertSame(d, r2, "Subsequent calls still return same instance");
        assertFalse(d.getIsPrimary(), "isPrimary remains false after subsequent call");
    }

    @Test
    public void toString_doesNotThrow() {
        DummyResponse d = new DummyResponse();
        String s = d.toString();
        assertNotNull(s, "toString should not return null");