Fulfill Purchase
To implement the fulfill purchase API using the SDK, implement one abstract method from the PurchaseController class: ProcessFulfillPurchase.
/// <summary>
/// Processes Fulfill Purchase requests.
/// </summary>
/// <returns>A <see cref="Task{T}"/> of <see cref="FulfillPurchaseResposne"/> or an exception if bill once purchases are not supported.</returns>
protected override Task<FulfillPurchaseResposne> ProcessFulfillPurchase(PurchaseRequest purchaseRequest);
request);