折扣单元集-DiscountItems union

折扣的基础单元集。一个基础单元可以是符合折扣资格的物品或先决条件，如collection或product或product_variant。

可能的类型

• [AllDiscountItems](https://shopify.dev/docs/admin-api/graphql/reference/discounts-and-marketing/alldiscountitems)
• [DiscountCollections](https://shopify.dev/docs/admin-api/graphql/reference/discounts-and-marketing/discountcollections)
• [DiscountProducts](https://shopify.dev/docs/admin-api/graphql/reference/discounts-and-marketing/discountproducts)