Unable to submit spark job as proxy user from zeppelin livy interpreter

I am using livy interpreter in zeppelin to submit a spark job. 

livy.impersonation.enabled is set to true and livy.spark.proxy.user is set to test. 

My expectation is that livy should use test user to submit spark job but it is using my Id. What is the property that I should set to achieve this?

Any help would be much appreciated.

Thanks,

Naveen