=act #13966 Change wrong default discardOld in UntypedActor become
Merge pull request #15068 from akka/wip-13966-become-discardOld-patriknw

=act #13966 Change wrong default discardOld in UntypedActor become
=pro #15021,#13755 Emit statsd events during build
!str #15063 Add Flow.Transformer interface

* Skip wrapping RecoveryTransformer elements in Try
* this will make it possible to use the same RecoveryTransformer interface
  for javadsl and scaladsl, which is important if we package building
  blocks in Transformer classes
* also avoids wrapper allocation
Merge pull request #15137 from ktoso/build-junit-reports-backport-ktoso

=pro junit xml reports backport
Merge pull request #15066 from akka/wip-15063-transformer-patriknw

!str #15063 Add Flow.Transformer interface
+str #15071 Add Flow.apply from a Future