Deprecated Transaction object has product field that can help to derminate source of transaction. I guess that Order.source field in new API has the same meaning but in API Explorer Order.source is omitted in the response.
AM i right that Order.source has the same meaning with Transaction.product?
What field i can use instead of old Transaction.product?
Transaction object: https://developer.squareup.com/reference/square/objects/Transaction
Order object: https://developer.squareup.com/reference/square/objects/Order