metafield:
Metafield
A [custom field](https://shopify.dev/docs/apps/build/custom-data),
including its `namespace` and `key`, that's associated with a Shopify resource
for the purposes of adding and storing additional information.
shopifyFunction:
ShopifyFunction!
The Shopify Function implementing the delivery customization.
title:
String!
The title of the delivery customization.