These fields are optional for refunding a gift card redemption:
billTo_postalCode
customerID
giftCard_escheatable
giftCard_groupID
Supported for card-present only.
giftCard_transactionPostingDate
giftCardActivationService_reconciliationID
invoiceHeader_clerkID
invoiceHeader_merchantDescriptorCountry
merchantDefinedData_mddField_1 and merchantDefinedData_mddField_2
merchantTransactionIdentifier
pos_terminalID
transactionLocalDateTime