curl --request PUT \
  --url https://api.bold-factory.com/v1/planning/purchaseOrders/{orderReference}/externalReference \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "externalReference": "<string>"
}
'

{
  "type": "https://api.bold-factory.com/errors/FILTER_PARSING_FAILED",
  "title": "Filter parsing failed",
  "status": 400,
  "detail": "The filter string could not be parsed or contains invalid column references: CreatedBy column does not exist.",
  "instance": "POST /v1/items/products/search",
  "code": "FILTER_PARSING_FAILED"
}