detectSubmenu() {
    const hasSubmenu = this.hasSubmenu;
    this.container.classList[hasSubmenu ? 'add' : 'remove']('has-submenu');
    this.decorateSubmenu(hasSubmenu);
    return hasSubmenu;
  }
/**
   * @private
   * @returns {boolean} true if this menu item contains a submenu structure.
   */
@private
@returns {boolean} true if this menu item contains a submenu structure.
@private @returns { boolean } true if this menu item contains a submenu structure .
detectSubmenu() {
    const hasSubmenu = this.hasSubmenu;
    this.container.classList[hasSubmenu ? 'add' : 'remove']('has-submenu');
    this.decorateSubmenu(hasSubmenu);
    return hasSubmenu;
  }
detectSubmenu ( ) { const hasSubmenu = this . hasSubmenu ; this . container . classList [ hasSubmenu ? 'add' : 'remove' ] ( 'has-submenu' ) ; this . decorateSubmenu ( hasSubmenu ) ; return hasSubmenu ; }
@private
 @returns {boolean} true if this menu item contains a submenu structure.
@private @returns { boolean } true if this menu item contains a submenu structure .