@Override
    public List<String> getServices() {
        if (!isRegistered.get()) {
            LOGGER.warning("Query instance must be at the stage that finish registry!");
            return Collections.emptyList();
        }
        return RegisterManager.INSTANCE.getServices();
    }
@Test
    public void getServices() {
        Assert.assertTrue(registerCenterService.getServices().isEmpty());
    }