Creates a new gift card transaction. The two most important fields for creating a new gift card transaction are the number of the gift card and the type of the transaction. The type determines what sort of transaction it is.
"REDEEMING" - Use this type when you want to redeem a certain amount from the gift card balance. The amount MUST be negative. If you want to add an amount to the balance use the "RELOADING" type.
"RELOADING" - Use this type when you load a new amount onto a gift card.
If the gift card does not have enough credit to honour the transaction a 422 HTTP status code will be returned.
Please populate the client_id field with a unique transaction identifier, to ensure that the transaction is safe from double-submit problems. See the tutorial for more information.