Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  ElasticContainer: Use 6.5.2 for V6_5 tests
  Upgrade elasticsearch-rest-client to 6.5.2

Change-Id: I5e4b027b73e8dc4da0b99d2eb200635d482f3a2d
tree: fd8743e375a2c8a6097ce760ac70664a6af48972
  1. java/
  2. javatests/