=str #15739 Hook-up grouped, groupedWithin, timerTransform to new DSL
=str #15738 Hook-up drop, dropWithin, take, takeWithin to new DSL
=str #15741 Hook-up conflate, expand, buffer, and FoldSink
Merge pull request #15838 from akka/wip-15739-15738-15741-patriknw

=str #15739 #15738 #15741 Hook-up more ops to new DSL