HV-2051 Use spotless maven plugin instead of formatter/impsorter/license check plugins

[marko-bekhta]

https://hibernate.atlassian.net/browse/HV-2051

This one is only to evaluate the option and not actually to apply the change ...
I thought that it would be better to test this on the Validator as it uses all 3 plugins and has a smaller codebase.
Best to look by commit (if looked at all 😅).

• Not all things that we are checking with checkstyle have an alternative (or at least I couldn't find one). I kept those rules in the checkstyle file so we can review them. I'll add a comment on that file so it's easier to find.
• I couldn't split the license header check from formatting; hence, the files with different licenses are not formatted... (I suspect that having multiple executions would do the trick, but I didn't want to go that route as I suppose the idea was to simplify the build and have fewer executions....)
• import sorting removes the comments. This means that the tags we have in the docs tests to include in the documentation file have to be excluded from spotless, resulting in those imports not being sorted (not a big deal, but a bit annoying 😃)
• While trying to figure out the patterns for XML headers I've noticed that the plugin does not always fail when there's a problem in the config. I had a bad regex that was capturing the license header itself resulting in infinite update of the same file (at least that is what I've seen while debugging). This resulted in the build just passing successfully and the files not affected (I'd rather it failed with a build error .... )

(this work is not complete: the maven properties and builds should also be updated to make it all work and I haven't done that here yet...)

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on licensing, please check here.

---

[hibernate-github-bot]

Thanks for your pull request!

This pull request appears to follow the contribution rules.

› This message was automatically generated.

[marko-bekhta]

@yrodiere I'll let you have a look at this one (probably whenever you have nothing interesting to look into 😄 )

[yrodiere]

• I couldn't split the license header check from formatting; hence, the files with different licenses are not formatted... (I suspect that having multiple executions would do the trick, but I didn't want to go that route as I suppose the idea was to simplify the build and have fewer executions....)
  [...]
• While trying to figure out the patterns for XML headers I've noticed that the plugin does not always fail when there's a problem in the config. I had a bad regex that was capturing the license header itself resulting in infinite update of the same file (at least that is what I've seen while debugging). This resulted in the build just passing successfully and the files not affected (I'd rather it failed with a build error .... )

Looks like we'd be better off keeping license header checks in checkstyle?

import sorting removes the comments. This means that the tags we have in the docs tests to include in the documentation file have to be excluded from spotless, resulting in those imports not being sorted (not a big deal, but a bit annoying 😃)

Annoying indeed... though it's quite rare that we include comments in docs code snippets, at least for Hibernate Search, so I suppose we can live with it.
Do you know if there's a bug report / feature request in Spotless regarding this?

Not all things that we are checking with checkstyle have an alternative (or at least I couldn't find one). I kept those rules in the checkstyle file so we can review them. I'll add a comment on that file so it's easier to find.

Will have a look, but if we need checkstyle for license header checks anyway, I suppose it's no big deal.