Contact is not logged in. The client makes an order, and set one of his contacts to be registrant of some service (exaple: registrant of some domain). This selected contact in my shopping cart, is the right contact 🙂
I have access to all contacts of that client in my shopping cart, also I can access to them via query in my hook, but I need to catch the id of selected contact from my shopping cart (by client), and send to my custom make hook.