curl --request PUT \
  --url https://production.trackstarhq.com/wms/returns/{return_id}/cancel \
  --header 'x-trackstar-access-token: <x-trackstar-access-token>' \
  --header 'x-trackstar-api-key: <x-trackstar-api-key>'

{
  "id": "id",
  "unused_fields": [
    "<string>"
  ],
  "data": {
    "id": "return_id",
    "warehouse_customer_id": "warehouse_customer_id",
    "created_date": "2022-01-01T00:00:00Z",
    "updated_date": "2022-01-02T05:05:05Z",
    "status": "cancelled",
    "raw_status": "raw_status",
    "order_id": "order_id",
    "notes": [
      "This is a note"
    ],
    "line_items": [
      {
        "inventory_item_id": "item_id",
        "sku": "sku",
        "expected_quantity": 1,
        "received_quantity": 1,
        "restocked_quantity": 1,
        "return_reason": "Too Small",
        "quantity": 0,
        "warehouse_id": "deprecated",
        "returned_date": "deprecated"
      }
    ],
    "shipments": [],
    "external_system_url": "https://example.com/return/123",
    "trackstar_tags": [
      "tag1",
      "tag2",
      {
        "tag3": "value3"
      }
    ],
    "additional_fields": {
      "key": "value"
    }
  }
}