Enterprise Contracts Automatic Renewal Process without Assignee

Summary:

We have configured automatic renewal for Enterprise contracts.

To renew the contracts we need to run "Automatically Renew Eligible Contracts and Contract Lines" process. which needs Assignee as mandatory parameter.

one of my contract does not have any assignee at header level, and I ran the process with Owner name as assignee and Contract got renewed as per the rules.

Experts! could you please let me know is it expected behavior and how the assignee works on enterprise contracts?