@Override
    public void unsubscribeService(Service service, Subscriber subscriber, String clientId) {
        throw new UnsupportedOperationException("No persistent subscribers");
    }
@Test
    void testUnsubscribeService() {
        assertThrows(UnsupportedOperationException.class, () -> {
            persistentClientOperationServiceImpl.unsubscribeService(service, subscriber, clientId);
        });
    }