Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Add support for Elasticsearch 7.1.0

Change-Id: I6bc8c176794e190ef26bce41780b1025fe923c04
tree: bfbd7e29be8b066008c221e4d81276ab917ebd34
  1. java/
  2. javatests/