public static function getUsedExtensionList()
    {
        $app = Application::getFacadeApplication();
        $db = $app->make('database')->connection();
        $stm = $db->executeQuery("select distinct fvExtension from FileVersions where fvIsApproved = 1 and fvExtension is not null and fvExtension <> ''");
        $extensions = [];
        while ($row = $stm->fetch()) {
            $extensions[] = $row['fvExtension'];
        }

        return $extensions;
    }