;
          });
        }

        /**
         * Evaluates the actual value for given item.
         *
         * @param {Object|string} item the item get value from.
         * @return {string} the item value.
         */
        _getValue(item) {
          return this.valuePath ? item[this.valuePath] : item;
        }

        /**
         * Evaluates the actual label for given item.
         *
         * @param {Object|string} item the item get label from.
         * @return {string} the item label.
   