protected function getConfigurationKey()
    {
        if (Registry::instanceExists(\OxidEsales\Eshop\Core\ConfigFile::class)) {
            $config = Registry::get(\OxidEsales\Eshop\Core\ConfigFile::class);
        } else {
            $config = new \OxidEsales\Eshop\Core\ConfigFile(getShopBasePath() . '/config.inc.php');
            Registry::set(\OxidEsales\Eshop\Core\ConfigFile::class, $config);
        }
        return $config->getVar('sConfigKey') ?: Config::DEFAULT_CONFIG_KEY;
    }