order_id: 1001
customer {
  id: 42
  email: "alice@example.com"
}
items {
  product_id: "sku-99"
  quantity: 2
  cents: 1999
}
items {
  product_id: "sku-100"
  quantity: 1
  cents: 999
}
shipping_address {
  street: "Main St"
  city: "Mountain View"
  zip: "94043"
}
metadata {
  key: "priority"
  value: 1
}