If you really want to use the the JIRA native User Picker field, you just update the display name to contain the username as well... or maybe add the email address as well. I have done this with several JIRA instances that we support.
If you want to use a custom field, you may opt to use a "Scripted Field" and code something that will give what you need.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot