[SPARK-13257] [Improvement] Scala naive Bayes example: check model after loading

[movelikeriver]

Refine naive Bayes example by checking model after loading it.
This is Java version, to be consistent with Python version in #11125

[holdenk]

So this usage text probably isn't the format we want, its pretty specific to each Spark release. Maybe look at some of the other files in this directory and see how they do their usage?

[holdenk]

Thanks for taking on this issue & fixing it across multiple languages.

A super minor thing is generally we try and have separate JIRAs for separate PRs - so in this case creating a sub task on the initial PR to also update Scala might be better from a tracking point of view (since when I went to look at this PR my first thought was that the issue had already been resolved).

You might also want to try running the scala linter locally on your code (e.g. ./dev/lint-scala) and make sure it conforms to the style rules.

[HyukjinKwon]

Hi @movelikeriver, are you able to proceed this further? If not, maybe it'd be better closed for now.

[AmplabJenkins]

Can one of the admins verify this patch?