@Test
public void testUnsubscribeIfNotifyNull() throws Exception {

    Assertions.assertThrows(IllegalArgumentException.class, () -> {
        final AtomicReference<Boolean> notified = new AtomicReference<Boolean>(false);
        URL url = new URL("dubbo", "192.168.0.1", 2200);
        abstractRegistry.unsubscribe(url, null);
        Assertions.fail("unsubscribe listener == null");
    });
}