@SuppressWarnings("unchecked")
public void testAddedOnDemand() {
assertEquals(0, docListeners.size());
DocumentEventRouter<Doc.N, Doc.E, ?> router = createRouter(doc);
assertEquals(0, docListeners.size());
ListenerRegistration firstReg = router.addAttributeListener(new DummyElm(),
mock(AttributeListener.class));
assertEquals(1, docListeners.size());
ListenerRegistration secondReg = router.addAttributeListener(new DummyElm(),
mock(AttributeListener.class));
assertEquals(1, docListeners.size());
firstReg.detach();
assertEquals(1, docListeners.size());
secondReg.detach();
assertEquals(0, docListeners.size());
}