Kafka Streams reducebykey and tumbling window - need final windowed KTable values

[Clive Cox]

Hi,
 I would like to process a stream with a tumbling window of 5secs, create 
aggregated stats for keys and push the final aggregates at the end of each 
window period to a analytics backend. I have tried doing something like:
  stream
        .map
        .reduceByKey(...
          , TimeWindows.of("mywindow", 5000L),...)
        .foreach         {            send stats
         }
But I get every update to the ktable in the foreach.
How do I just get the final values once the TumblingWindow is complete so I can 
iterate over them and send to some external system?
Thanks,
 Clive
PS Using kafka_2.10-0.10.0.0