Use the latest v2 Java protobuf bindings.
Use the latest v2 Java protobuf bindings.

This will keep us up to date with new protoc versions. Since new
versions of the Java bindings generally work with old versions of
protoc this should not break the build when a new version arrives.

Change-Id: I8508ad470d0dd4169bb3c0f56470b24da75a5073

google/rich-test-results