Reserves a refund before the payment rail is asked for it: only the paid lot's free principal (neither held nor
consumed) can be refunded, so a refund of committed funds is refused with what can be refunded now. A refund id
reserved already answers existing only for its own scope, lot and amount; of two scopes racing for one id, one
reserves it and the other is refused as conflict, its lot untouched. Confirm or revert it with
completeLotRefund.
Reserves a refund before the payment rail is asked for it: only the paid lot's free principal (neither held nor consumed) can be refunded, so a refund of committed funds is refused with what can be refunded now. A refund id reserved already answers
existingonly for its own scope, lot and amount; of two scopes racing for one id, one reserves it and the other is refused asconflict, its lot untouched. Confirm or revert it with completeLotRefund.