Use case
Return the sum of the time spent of the issues under the epic in hours.
Expression
Create and configure a Smart field using this expression in General parsing mode:
%{%{issue.issueType} = "Epic" ? sum(append(fieldValue({issue.timeSpent}, issuesUnderEpic()), [0])) / 60 : null}
If the resulting number from the expression contains too many decimal numbers, feel free to select one of the available display formats or to configure it manually.
