@Override
    public Collection<Subscriber> getSubscribers(String namespaceId, String serviceName) {
        Collection<Subscriber> result = new LinkedList<>(
                subscriberServiceLocal.getSubscribers(namespaceId, serviceName));
        if (memberManager.getServerList().size() > 1) {
            getSubscribersFromRemotes(namespaceId, serviceName, result);
        }
        return result;
    }
@Test
    void testGetSubscribersByServiceWithLocal() {
        Collection<Subscriber> actual = aggregation.getSubscribers(service);
        assertEquals(1, actual.size());
        assertEquals("local", actual.iterator().next().getAddrStr());
    }