DiscountShippingDestinationSelection union
The selection of shipping countries to which this discount applies.
Possible types
[DiscountCountries](https://shopify.dev/docs/admin-api/graphql/reference/discounts-and-marketing/discountcountries)
[DiscountCountryAll](https://shopify.dev/docs/admin-api/graphql/reference/discounts-and-marketing/discountcountryall)