This function returns an issue list containing issues which are linked to the same epic as the current issue.
The current issue will be included in the output, except if it is an epic itself.
Only standard issues (no sub-tasks) will be returned and duplicates are being removed.
issuesUnderEpic() #Output: Issue list
Variant where you additionally define an issue list.
Duplicated issues are filtered from the output.
issuesUnderEpic(issueList) #Output: Issue list
Variant where you define issue keys instead.
issuesUnderEpic(issueKeys) #Output: Issue list