@Override
 public void entryUpdated(EntryEvent<K, V> entry) {
   K k = entry.getKey();
   ChoosableSet<V> entries = cache.get(k);
   if (entries != null) {
     entries.add(entry.getValue());
   }
 }
 @Override
 public void entryRemoved(EntryEvent<K, V> entry) {
   removeEntry(entry.getKey(), entry.getValue());
 }
 @Override
 public void entryAdded(EntryEvent<K, V> entry) {
   addEntry(entry.getKey(), entry.getValue());
 }