Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Upgrade elasticsearch-rest-client to 7.3.1
  Add .gitreview file

Update the newly added .gitreview file to point to stable-2.16.

Change-Id: I9ca52ec3d90dea1b44321be4eb648448abafff1e
tree: 2a482d2774d1472be41bdd2a898ad1097bcb41c1
  1. java/
  2. javatests/