connectedCallback() {
      super.connectedCallback();
      this.setAttribute('role', 'group');

      this.initComplete.then(() => {
        this.__isInitialModelValue = false;
        this.__isInitialSerializedValue = false;
        this.__initInteractionStates();
      });
    }
@type {{modelValue?:{[key:string]: any}, serializedValue?:{[key:string]: any}}}