ProvidedServiceListener bad = new ThrowingListener();
ps.addListener(bad);
ProvidedServiceListener l2 = new TotalCountingListener();
ps.addListener(l2);
ProvidedServiceListener l3 = new AppendingListener();
ps.addListener(l3);
// Check initial valued are untouched
assertEquals(0, registrations);
assertEquals(0, unregistrations);
assertEquals(0, updates);