post https://marketplace.walmartapis.com/v3/returns//refund
This API allows sellers to issue refund against a return order. Multiple return order lines can be refunded in one request.
Note: Sellers can use the Refund Order Lines API for all non-exception category items, including adjustments that seller needs to determine a partial refund amount. Especially for exception category items: HAZMAT, OTHER and FREIGHT that are not eligible for the Marketplace Returns Program.