s to set the selection. Instead use
         * `selected`.
         *
         * @attribute selectedItem
         * @type Object
         * @default null
         */
        selectedItem: null,

        /**
         * In single selection, this returns the model associated with the
         * selected element.
         * Note that you should not use this to set the selection. Instead use
         * `selected`.
         *
         * @attribute selectedModel
         * @type Object
         * @default null
   