How to create a subtask when in a task it add a flag?

[Jose Luna López]

I would like to add a subtask automatically when I add a flag on a issue. 

We had the plugin ScriptRunner.

[larry.lowe]

@Jose_Luna_López

1. I used scriptrunner to create a new listener
2. Choose the option to create a sub-task from the listener templates
3. Select "Issue Updated" as the event
4. Enter the below code for the "Condition":

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.Issue
import com.atlassian.jira.issue.ModifiedValue
import com.atlassian.jira.issue.util.DefaultIssueChangeHolder

def change = event?.getChangeLog()?.getRelated("ChildChangeItem").find {it.field == "Flagged"}
if (change && ('Impediment' in cfValues['Flagged']*.value)){
return true;
}

 I was able to get this working in Jira Data Center 7.13

[Nic Brough -Adaptavist-]

I am not sure this is possible - if adding a flag fires an event, then you can write a listener to catch the event and create a subtask, but I have a feeling no event is fired by flagging or un-flagging.