Problem: in your JSM request event configuration you would like to take different actions depending on whether the comment is created or updated.
Solution: Make use of createdEvent comment property like shown below:
#if ($issue.addedComment.createdEvent) Added new comment: $issue.addedComment.renderedBody #else Modified comment: $issue.addedComment.renderedBody #end
The createdEvent property is only valid for JSM request events (comment added - any, public comment added, private comment added)