Create a refund for a given payment.

Creates a new refund object and immediately begins processing the
refund.

Unlike adding a payment, which is not processed until the payment is
captured, this request will have immediate financial side effects.

HTTP Status Code

This endpoint always returns a 201 status code if the Refund was
submitted for processing, even if the refund attempt fails, because a
Refund object is created on the Forage server to preserve a record of
the failed Refund attempt. Therefore, even if your app receives a 201
HTTP status code from the Forage Payments API, it will still need to
check the status of the Refund response is succeeded. If the
status is failed, please check the refund_errors field in the
response for more detail.