Returns child issues (on Portfolio hierarchy) of issues specified by the provided subquery. See also: portfolioParentOf()
Note: Since you need to enclose the provided subquery using doble quotes, you must to escape any doble quotes using in the subquery by preceding a backslash after the double quotes, alternatively you can use a single quote in some cases.
Let's see an example...
This will not work
issue IN portfolioChildOf("resolution = "Won't Do" AND status = Closed")
Searches for childrens of already closed issues which their resolution have been set to "Won't Do"
This will work perfectly
issue IN portfolioChildOf("resolution = \"Won't Do\" AND status = Closed")
Searches for childrens of already closed issues which their resolution have been set to "Won't Do"
issue IN portfolioChildOf("status = 'In Progress' AND reporter = currentUser()")
Searches for childrens of in progress issues reporter by me
This function does not traverse the link from Epic to Story. To also find stories, or subtask you should use this function in conjuntion with issuesInEpics() or subtasksOf() JQL functions.