When a customer checks out using the cash payment option, the Generic Payment webhook sends a CASH REQUEST transaction type to the payment gateway. The provider can respond with the response code 1000, which acknowledges the payment request. After the payment is received, the provider can update the order with payment details using the updateOrder endpoint in the Admin API.

If payment has already occurred when the webhook request is received, the provider can send the response code 4000 in the webhook response, indicating that the sale is complete. In such cases, updateOrder calls are not needed. If response code 4000 is received, the order is marked as ready for fulfillment.