: String,

            /**
             * Current filter value.
             */
            value: {
              type: String,
              notify: true
            },

            /** @private */
            _connected: Boolean
          };
        }

        /** @protected */
        connectedCallback() {
          super.connectedCallback();
          this._connected = true;
        }

        static get observers() {
          return ['_filterChanged(path, value, _connected)'];
        }

        /** 