How do I limit which fields show up in Scriptrunner Issue picker?

[Connie Leuderalbert]

I have created an issue picker field which pulls in values from another Jira project.  That works great. 

However, my customer does not want to see the issue key, this would be confusing for him.  How do I limit the dropdown to only show the summary?  All of the summaries are unique, so there is no concern about having a summary linked to 2 issue keys.  Do I use a behavior?  If so, how do I set it up.

Please go step-by-step.  This is my first issue picker and the documentation I an finding is geared to people really familiar with scriptrunner in general.

Thanks,

Connie