jira - first name only in smart value

[Gavin]

{{reporter.displayName}}, - shows first and last name

But is there a way to show just the first name?

this question was asked https://community.atlassian.com/t5/Jira-Service-Management/Using-firstname-of-assignee-instead-of-firstname-and-lastname/qaq-p/1761353. talks about using {{issue.assignee.displayName.split(" ").first}}. however when I use it I get nothing displayed.

[Florian Bonniec]

Hi you can try using 

{{reporter.displayName.substringBefore(" ")}}

Can you give me a example of the format of a display name ?

FirstName Last name or FirstName, LastName

Regards