OptionalextThe unit price of the product, including line-level discounts.
OptionalproductThe product variant or unit name.
The quantity purchased.
OptionalskuThe SKU (SKU/barcode/GTIN/MPN or external id).
When present it takes precedence over extProductId on the wire.
The external product ID.
Kept for backward compatibility. When
skuis not provided, this value is sent as theskuof the correspondingline_itemsentry. At least one ofskuorextProductIdis required.