If a merchant issues a refund, does it show up in both the Refunds List and Retrieve Payment endpoint? Are there situations in which it may show up in one, but not the other (such as Cash, Check, or other Tender Types)?
The use case is an external app storing / caching payments where refunds need to update the stored payments to keep accurate sales figures. If refunds show up in both places, then it seems the best way to update stored payments in this use case is to load the Refunds List periodically and update the stored payment using the Retrieve Payment endpoint.