public function isForeignVatClass($vatClassId)
    {
        $shopSettings = $this->config->getShopSettings();
        $foreignVat = $shopSettings['foreignVat'];
        $foreignVatClasses = $shopSettings['foreignVatClasses'];
        return $foreignVat !== PluginConfig::ForeignVat_No && in_array($vatClassId, $foreignVatClasses);
    }