notificationCenter.addObserver("notification2", o4, STRONG_REFERENCE);
notificationCenter.postNotification("notification1", ObjectUtils.toMap("key1", "value1"));
assertResult("observer1: notification1 {'key1':'value1'}", "observer2: notification1 {'key1':'value1'}");
notificationCenter.postNotification("notification2", ObjectUtils.toMap("key2", "value2"));
assertResult("observer3: notification2 {'key2':'value2'}", "observer4: notification2 {'key2':'value2'}");
notificationCenter.removeObserver(o4);
notificationCenter.postNotification("notification1", ObjectUtils.toMap("key1", "value1"));
assertResult("observer2: notification1 {'key1':'value1'}");
notificationCenter.postNotification("notification2", ObjectUtils.toMap("key2", "value2"));
assertResult("observer3: notification2 {'key2':'value2'}");
notificationCenter.postNotification("notification1", ObjectUtils.toMap("key1", "value1"));
assertResult();
notificationCenter.postNotification("notification2", ObjectUtils.toMap("key2", "value2"));
assertResult();
notificationCenter.postNotification("notification1", ObjectUtils.toMap("key1", "value1"));
assertResult("observer1: notification1 {'key1':'value1'}", "observer2: notification1 {'key1':'value1'}");
notificationCenter.postNotification("notification2", ObjectUtils.toMap("key2", "value2"));
assertResult("observer3: notification2 {'key2':'value2'}", "observer4: notification2 {'key2':'value2'}");