Enforce Code Format with Checkstyle and/or Spotless and/or Google Java Format

[vorburger]

Given that this project is starting to get PR contributions, it would IMHO be good to enforce a good format.

I'm already working on a PR with Checkstyle - which I'm hoping is quick - because I'll just copy/paste this and the respective lines from the MariaDB4j pom.xml .

This ch.vorburger.exec code historically actually originates from MariaDB4j and used to be formatted like that, so I expect that it should need relatively few changes only.

In #126 @mosesn has raised possibly using https://github.com/diffplug/spotless as a possible alternative. I am personally less motivated for doing the work for that, just because it would take me longer to figure out how to set up. (But years ago I actually was a Google Summer of Code GSoC mentor advising a student to add Spotless to https://github.com/apache/fineract/ and it seemed great, so I have no strong objections to replace Checkstlye with Spotless - if someone else wants to put in the work for it!) I don't suppose Spotless can use a Checkstyle configuration, can it?

An alternative could be using https://github.com/google/google-java-format. I have adopted that in my latest project, for https://github.com/enola-dev/enola, see https://docs.enola.dev, and quite like it too. I haven't looked much into the available Maven plugins, although looking at https://github.com/google/google-java-format#third-party-integrations it seems like Spotless may actually use Google Java Format internally? I'm OK if someone wants to raise a PR for that.

BTW on this sort of things, for Enola.dev I've also had loads of fun with a .pre-commit-config.yaml, and loads of related configuration files like .editorconfig and .prettierrc.yaml and .clang-format and .markdownlint.yaml and .protolint.yaml, but I think for this ch.vorburger.exec project I want to keep the "barrier to entry" lower by sticking to a pure Java and fully Maven integrated approach, only.

Thoughts - anyone?

[vorburger]

#132 adds Checkstyle - just because that was the fastest for me to do, and prevents discrepancies.

I'm fairly open to PRs which would propose to remove Checkstyle to replace it with something else.