public function getSerie()
    {
        if ($this->_oSerie !== null) {
            return $this->_oSerie;
        }
        $oSerie = oxNew(\OxidEsales\Eshop\Application\Model\VoucherSerie::class);
        if (!$oSerie->load($this->oxvouchers__oxvoucherserieid->value)) {
            throw oxNew(\OxidEsales\Eshop\Core\Exception\ObjectException::class);
        }
        $this->_oSerie = $oSerie;

        return $oSerie;
    }