public function headerMenu()
    {
        if ($this->headerMenu === null) {
            $dashboardConfig = $this->dashboardConfig();

            if (isset($dashboardConfig['secondary_menu'])) {
                $this->headerMenu = $this->createHeaderMenu($dashboardConfig['secondary_menu']);
            } else {
                $this->headerMenu = $this->createHeaderMenu();
            }
        }

        return $this->headerMenu;
    }