* Add the delegate to the map. Other {@code WrappedCollection} methods should call this method
     * after adding elements to a previously empty collection.
     *
     * <p>Subcollection add the ancestor's delegate instead.
     */
    void addToMap() {
      if (ancestor != null) {
        ancestor.addToMap();
      } else {
        map.put(key, delegate);
      }
    }

    @Override
    public int size() {

     * Add the delegate to the map. Other {@code WrappedCollection} methods should call this method
     * after adding elements to a previously empty collection.
     *
     * <p>Subcollection add the ancestor's delegate instead.
     */
    void addToMap() {
      if (ancestor != null) {
        ancestor.addToMap();
      } else {
        map.put(key, delegate);
      }
    }

    @Override
    public int size() {