@Override
    public void subscribe(URL url, NotifyListener listener) {
        super.subscribe(url, listener);
        subscribed(url, listener);
    }
@Test
    void testSubscribe() {
        // verify listener
        final URL[] notifyUrl = new URL[1];
        for (int i = 0; i < 10; i++) {
            registry.register(serviceUrl);
            registry.subscribe(consumerUrl, urls -> {
                notifyUrl[0] = urls.get(0);

                Map<URL, Set<NotifyListener>> subscribed = registry.getSubscribed();
                assertEquals(consumerUrl, subscribed.keySet().iterator().next());
            });
            if (!EMPTY_PROTOCOL.equalsIgnoreCase(notifyUrl[0].getProtocol())) {
                break;
            }
        }
        assertEquals(serviceUrl.toFullString(), notifyUrl[0].toFullString());
    }