Currently the events Resources have five different issue-related event types: issue_update, issue_comment, report_issue, start_follow_issue and stop_follow_issue. Now, the comment-related ones have a comment id in their description field, but none of them have an issue id. Please add issue ids to all issue-related events. And while at it, issue titles would also be a nice addition so that you don't need to make another API call just to get those.
Issue #4948 closed