docs: protected void doNotifyListenersOfChangedValues(Map<K, R> oldValues, Map<K, R> newValues) {
          List<MapValueChangeListener<K, R>> listenersCopy = new ArrayList<MapValueChangeListener<K, R>>(listeners);
          Map<K, R> oldUnmodifiable = Collections.unmodifiableMap(oldValues);
          Map<K, R> newUnmodifiable = Collections.unmodifiableMap(newValues);
          for (MapValueChangeListener<K, R> listener : listenersCopy) {
              listener.valuesChanged(this, oldUnmodifiable, newUnmodifiable);
          }
      }