Optionalcard_type?: SumUp.Transactions.CardTypeOptionalclient_transaction_id?: stringOptionaltransaction_id?: SumUp.Transactions.TransactionIDOptionaltype?: "PAYMENT" | "REFUND" | "CHARGE_BACK"Type of the transaction for the registered user specified in the user property.
Optionaluser?: stringEmail address of the registered user (merchant) to whom the payment is made.
Client-specific ID of the transaction.