Merge branch 'stable-2.16'

* stable-2.16:
  Remove redundant StandardKeyEncoder reference
  Format build files with buildifier 0.19.2
  E2E integration test using Kafka docker container
  AbstractKafkaSubcriber: Add listener for dropped events
  Removed unused PeerInfoStrategy enum

Change-Id: Icded855cba1d1a0041605b9081712ea1f188726d