curl --request GET \
  --url https://api.upwell.com/api/rest/shipments/{shipmentId}/documents

{
  "shipmentDocumentsByShipmentId": [
    {
      "createdAt": "<unknown>",
      "documentId": "<string>",
      "documents": [
        {
          "id": "<string>",
          "sourceSystem": "<string>",
          "sourceSystemId": "<string>",
          "type": "<string>",
          "visibleToCarrier": true,
          "visibleToCustomer": true
        }
      ],
      "file": {
        "filename": "<string>",
        "id": "<string>",
        "url": "<string>"
      },
      "id": "<string>",
      "shipment": {
        "id": "<string>",
        "number": "<string>"
      },
      "updatedAt": "<unknown>"
    }
  ]
}