New field for discount classes on DraftOrderPlatformDiscount

The discountClass field in the DraftOrderPlatformDiscount object has been deprecated. Please use the discountClasses field instead, which allows for the representation of multiple discount classes associated with the backing price rule of the DraftOrderPlatformDiscount.

To determine the specific impact of a DraftOrderPlatformDiscount on a draft order, continue using the presentationLevel field.