An ApplePayLineItem dictionary representing the total price for the purchase. Set the label to the merchant’s name, and the amount to the total price. The amount must be greater than zero.
A sequence of ApplePayLineItem dictionaries. Use ApplePayLineItem dictionaries to represent all other costs or discounts. Do not use line items to represent the individual items purchased by the user. Instead, combine all the purchases into a single subtotal item. Use additional line items to represent other costs or discounts (tax, shipping, coupons, and so forth.). If you do not have any additional costs or discounts, do not use this argument. Set the newTotal argument with the total cost of all the purchased items, and either pass an empty array or null for newLineItems.