public void testIdentityHashMapClassObject() {
        Map<Class, Class> map = new IdentityHashMap<Class, Class>();
        for (int i = 0; i < COUNT; i++) {
            Class oldValue = map.put(CLAZZ, CLAZZ);
            Class value = map.get(CLAZZ);
        }
    }
Just to verify testHashMapClassObject is fastest. Ignore this test.
EventBusTest/src/org/greenrobot/eventbus/ClassMapPerfTest.java