Underpayments can be programmatically accepted through this API endpoint in two different ways:
a. To accept an underpayment at current value, send only a
checkout_id in the body request.
b. To get a quote for current value of an underpayment and then accept that quote:
- First send
auto_confirm: false, which will return a quote
- To accept that quote, send
idfrom last step).