ON PROTOBUFS
This maven module has core protobuf definition files ('.protos') used by hbase
Spark.

Generation of java files from protobuf .proto files included here is done apart
from the build. Run the generation whenever you make changes to the .orotos files
and then check in the produced java (The reasoning is that change is infrequent
so why pay the price of generating files anew on each build.

To generate java files from protos run:

 $ mvn compile -Dcompile-protobuf
or
 $ mvn compile -Pcompile-protobuf

After you've done the above, check it and then check in changes (or post a patch
on a JIRA with your definition file changes and the generated files). Be careful
to notice new files and files removed and do appropriate git rm/adds.