fix(medusa,medusa-fulfillment-webshipper): Item to Webshipper line mapping (#3879)

* fix(medusa): Add missing variant relation on items

* fix: Webshipper fulfillment service

* Create kind-singers-travel.md

* Only add props if present

* add tests

packages/medusa/src/api/routes/store/swaps/create-swap.ts

@@ -9,13 +9,13 @@ import {
 } from "class-validator"
 import { defaultStoreSwapFields, defaultStoreSwapRelations } from "."
 
+import { Type } from "class-transformer"
+import { MedusaError } from "medusa-core-utils"
 import { EntityManager } from "typeorm"
 import IdempotencyKeyService from "../../../../services/idempotency-key"
-import { MedusaError } from "medusa-core-utils"
 import OrderService from "../../../../services/order"
 import ReturnService from "../../../../services/return"
 import SwapService from "../../../../services/swap"
-import { Type } from "class-transformer"
 import { validator } from "../../../../utils/validator"
 
 /**
@@ -145,6 +145,7 @@ export default async (req, res) => {
                       "swaps",
                       "swaps.additional_items",
                       "swaps.additional_items.variant",
+                      "swaps.additional_items.variant.product",
                       "swaps.additional_items.tax_lines",
                     ],
                   })