@Override
    public boolean isCallable(NamingEvent event) {
        if (event == null) {
            return false;
        }
        NamingChangeEvent changeEvent = (NamingChangeEvent) event;
        return changeEvent.isAdded() || changeEvent.isRemoved() || changeEvent.isModified();
    }
@Test
    public void testCallable() {
        NamingSelectorWrapper selectorWrapper = new NamingSelectorWrapper(null, null);
        InstancesDiff instancesDiff = new InstancesDiff(null, Collections.singletonList(new Instance()), null);
        NamingChangeEvent changeEvent = new NamingChangeEvent("serviceName", Collections.emptyList(), instancesDiff);
        assertTrue(selectorWrapper.isCallable(changeEvent));
        changeEvent.getRemovedInstances().clear();
        assertFalse(selectorWrapper.isCallable(changeEvent));
    }