protected function _getMenuFiles()
    {
        $editionPathSelector = new EditionPathProvider(new EditionRootPathProvider(new EditionSelector()));
        $fullAdminDir = $editionPathSelector->getViewsDirectory() . 'admin' . DIRECTORY_SEPARATOR;
        $menuFile = $fullAdminDir . 'menu.xml';

        // including std file
        if (file_exists($menuFile)) {
            $filesToLoad[] = $menuFile;
        }

        // including custom file
        if (file_exists($fullAdminDir . 'user.xml')) {
            $filesToLoad[] = $fullAdminDir . 'user.xml';
        }

        // including module menu files
        $path = getShopBasePath();
        $modulelist = oxNew(\OxidEsales\Eshop\Core\Module\ModuleList::class);
        $activeModuleInfo = $modulelist->getActiveModuleInfo();
        if (is_array($activeModuleInfo)) {
            foreach ($activeModuleInfo as $modulePath) {
                $fullPath = $path . "modules/" . $modulePath;
                // missing file/folder?
                if (is_dir($fullPath)) {
                    // including menu file
                    $menuFile = $fullPath . "/menu.xml";
                    if (file_exists($menuFile) && is_readable($menuFile)) {
                        $filesToLoad[] = $menuFile;
                    }
                }
            }
        }

        return $filesToLoad;
    }