public function mainMenu()
    {
        if ($this->mainMenu === null) {
            $options = null;

            if ($this instanceof DashboardContainerInterface) {
                $dashboardConfig = $this->dashboardConfig();

                if (isset($dashboardConfig['secondary_menu'])) {
                    $options = $dashboardConfig['secondary_menu'];
                }
            }

            $this->mainMenu = $this->createMainMenu($options);
        }

        return $this->mainMenu;
    }