无法找到如何添加优惠券到paypal网站亲结帐流程

Question

我已阅读并测试了过去2天如何将paypal网站专业版整合到我当前的网站。

我正在使用paypal最新的SDK，可以下载：https://www.x.com/developers/paypal/documentation-tools/paypal-sdk-index

到目前为止，我已设法添加运输/ CC详细信息，项目详细信息，税务详细信息以及其他所有内容。我唯一的问题是如何添加优惠券。我到处寻找一种方法，我找不到它。

我正在尝试整合直接付款。并快递退房 - 目前我正在进行直接付款

这是我到目前为止所获得的代码，其中大部分都位于他们的示例文件中。

$firstName = $_POST['firstName'];
$lastName = $_POST['lastName'];

$address = new AddressType();
$address->Name = "$firstName $lastName";
$address->Street1 = $_POST['address1'];
$address->Street2 = $_POST['address2'];
$address->CityName = $_POST['city'];
$address->StateOrProvince = $_POST['state'];
$address->PostalCode = $_POST['zip'];
$address->Country = $_POST['country'];
$address->Phone = $_POST['phone'];

$shippingTotal = new BasicAmountType($currencyCode, 25);
$handlingTotal = new BasicAmountType($currencyCode, 0);
$insuranceTotal = new BasicAmountType($currencyCode, 0);

$paymentDetails = new PaymentDetailsType();
$itemTotalValue = 0;
$taxTotalValue = 0;

$itemTotalValue += 15 * 2; 
$taxTotalValue += 0 * 2;
$itemDetails = new PaymentDetailsItemType();
$itemDetails->Name = 'First Item';
$itemDetails->Amount = new BasicAmountType($currencyCode, 15);
$itemDetails->Quantity = 2;
$itemDetails->ItemCategory = 'Digital';
$itemDetails->Tax = new BasicAmountType($currencyCode, 0);  

$paymentDetails->PaymentDetailsItem[0] = $itemDetails;  
//}

$orderTotalValue = $shippingTotal->value + $handlingTotal->value +
$insuranceTotal->value +
$itemTotalValue + $taxTotalValue;

$paymentDetails->ShipToAddress = $address;
$paymentDetails->ItemTotal = new BasicAmountType($currencyCode, $itemTotalValue);
$paymentDetails->OrderTotal = new BasicAmountType($currencyCode, $orderTotalValue);
$paymentDetails->TaxTotal = new BasicAmountType($currencyCode, $taxTotalValue);
$paymentDetails->PaymentAction = $_REQUEST['paymentType'];

$paymentDetails->HandlingTotal = $handlingTotal;
$paymentDetails->InsuranceTotal = $insuranceTotal;
$paymentDetails->ShippingTotal = $shippingTotal;

if(isset($_REQUEST['notifyURL']))
{
$paymentDetails->NotifyURL = $_REQUEST['notifyURL'];
}

我已经挖过他们的课程并找到了一个班级名称：OfferCouponInfoType

这似乎做了我想要实现的目标，但我不知道如何使用它。