Improve Actual Completion Date for Taks

Actual Completion Date (ACD) of a task is influenced by all child items: tasks, sub-tasks , sub-sub task etc and the connected issues.

ACD should be always the biggest ACD of all sub items, independently of the time of creation of the ACD on the sub item.

As add on: it would be beneficial if the change of the ACD on the task, triggered by a child object, is shown in the update stream.