PaymentType indicates the form of payment used for Merchant-provided payment method. Action must also provide a display name for the payment method.

PAYMENT_TYPE_UNSPECIFIED Unspecified payment type.
PAYMENT_CARD A credit/debit or prepaid card.
BANK Payment method is a bank account.
LOYALTY_PROGRAM Payment method is a loyalty program.
CASH Payment method is cash.
GIFT_CARD Payment method is a gift card.
WALLET Third party wallet, i.e. Paypal