@Override
    public Set<Entry<K, V>> entrySet() {
        // custom class needed here to handle entrySet mutators
        return new PersistenceAwareEntrySet<Entry<K,V>>(super.entrySet());
    }
Be aware that removing a property through the iterator of the returned key set might cause unexpected behavior,
as not all event handlers will be notified with all data required for cache updates to be processed.
xmppserver/src/main/java/org/jivesoftware/openfire/group/DefaultGroupPropertyMap.java