Progress eclipse cleanup
This revives the interest in Eclipse JDT CleanUp.
- The implementation is rooted in https://github.com/diffplug/spotless/compare/main...issue_292, but I would pursue the work in a forked repository.
- This is concurrent to my work in CleanThat, integrating various refactoring/cleanups engines (https://github.com/solven-eu/cleanthat/pull/423)
- Merging would probably waits the rework of Eclipse integration in Spotless https://github.com/diffplug/spotless/pull/1524
- This is a direct answer to https://github.com/diffplug/spotless/issues/292
- Unittests in _ext/eclipse-jdt are not available to myself from Intellij (they are grayed, like in case of classpath issue, hence not detected as source/unitTests). Is there a tips to get them working? (IntelliJ)

I resynced the branch with Spotless main.
@nedtwigg I had issues making it running in Cleanthat. Given the boilterplates around Eclipse integration, I feel preferable to drop Eclipse Cleanup from CleanThat, and get Cleanthat relying on Spotless.
As it stands, this PR holds core integration, but not availability through build options (Gradle, Maven, etc).
Do you prefer I open a separate PR for build-systems integrations ? (I will start with Eclipse). Or is it OK/preferable to have the whole thing in a single PR?
Single PR is fine.
This would help https://github.com/diffplug/spotless/issues/1379#issuecomment-1406192077
Unittests in _ext/eclipse-jdt are not available to myself from Intellij (they are grayed, like in case of classpath issue, hence not detected as source/unitTests). Is there a tips to get them working? (IntelliJ)
Any idea @nedtwigg ?
That whole project structure is about to be nuked. Everything in the _ext is becoming just a plain old sourceSet of lib-extra in #1524 which I will merge later today.
This is still quite a long way to go.
- Enable customization/selection of CleanUp rules
- Migration to updated Eclipse. (e.g. around
Indexer.getInstance().enableAutomaticIndexing(false);) - There was no unitTest in the initial work for cleanup (but there was for organizeImports). Hence, I'm not confident the minimal work was working fine.