Apache Beam's Reshuffle was marked as deprecated in May 2017 with the note
For internal use only; no backwards compatibility guarantees.
In addition, the DataflowRunner installs a ReshuffleOverrideFactory
which I'm unclear of how changes the reshuffling.
Anyway, the JavaDoc doesn't mention what to use instead. How are users supposed do deal with ParDo transforms with high fan out in general and on Dataflow?