Client Java program to reach internet through proxy using kerberos/Keytab authentication

Question

I develop a POC to do exactly what's mentionned in this topic's title.
For this, I've found jumarko sample which is working perfectly. Many thanks to him for this sample :).
However jumarko's sample uses callbackhandler implemetation. Which is a login/password authentication.
In my case, I'd like to use a keytab authentication instead of.
Could someone advise which interface or which system.property should I use to get keytab authentication ?
Many thanks in advance for your kind assist,