tree ed8d33db4dd63fc0baa904683059472fd77dfe78
parent 54748c4f733a0e2d8ad344a3b566359752cb666f
author Geneviève Bastien <gbastien+lttng@versatic.net> 1574289999 -0500
committer Genevieve Bastien <gbastien+lttng@versatic.net> 1578063838 -0500

weighted tree: Add the group by to weighted tree

It returns an optional group descriptor to describe the groups, this
will have an effect only if the elements are instances of ITree.

[added] Support of group by for the weighted tree set

Change-Id: Ifcff68cf366cc739799ed5f109337fd44e2ca292
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/153094
Tested-by: CI Bot
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>