public function addBaseParams()
    {
        $request = $this->getPayPalRequest();
        $payPalConfig = $this->getPayPalConfig();

        $request->setParameter("CALLBACKVERSION", "84.0");
        $request->setParameter("LOCALECODE", $this->getLang()->translateString("OEPAYPAL_LOCALE"));
        // enabled guest buy (Buyer does not need to create a PayPal account to check out)
        $request->setParameter("SOLUTIONTYPE", ($payPalConfig->isGuestBuyEnabled() ? "Sole" : "Mark"));
        $request->setParameter("BRANDNAME", $payPalConfig->getBrandName());
        $request->setParameter("CARTBORDERCOLOR", $payPalConfig->getBorderColor());

        $request->setParameter("RETURNURL", $this->getReturnUrl());
        $request->setParameter("CANCELURL", $this->getCancelUrl());

        if ($logoImage = $payPalConfig->getLogoUrl()) {
            $request->setParameter("LOGOIMG", $logoImage);
        }

        $request->setParameter("PAYMENTREQUEST_0_PAYMENTACTION", $this->getTransactionMode());
    }