This is an issue with REST API, I would raise a support case to tableau. You can't get the luid from the API or from the repository, so I have no idea other than call support
Tamas, thank you for the answer.
Actually I've asked a Tableau Doctor this question at Tableau Conference On Tour in Japan but I couldn't get an answer then and there.
He raised support case for me so I'm waiting for a contact from support.