generate proto file

[j143]

discussion points:

1. the generated java file is not taking the license header
2. Content seems to be a bit different from the older version of generated java file. (is there a way to test it)
3. Is this generation step going to happen every time we run mvn package

Solves #1578

[Baunsgaard]

overall i think this seems nice.
We can just add that license is not needed in this file.