public function isValid()
    {
        $payPalRequest = $this->getPayPalRequest();
        $payPalResponse = $this->getPayPalResponse();
        $shopOwnerUserName = $this->getShopOwnerUserName();
        $receiverEmailPayPal = $payPalRequest[self::RECEIVER_EMAIL];

        return ($payPalResponse->isPayPalAck() && $receiverEmailPayPal == $shopOwnerUserName);
    }