Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Upgrade bazlets to latest stable-2.16 to build with 2.16.18 API
  Bump Bazel version to 3.1.0

Change-Id: I13c75cdbcc9edfd5bbbd2682586eb8767c30806d
tree: b001fa7ea5c055bf91ed142cd89f0587698bc070
  1. .gitignore
  2. .settings/
  3. BUILD
  4. LICENSE
  5. src/