#1662 - Migrate to Maven 4

[mvolikas]

#1662 Changes for Maven 4 compatibility following the official migration guidelines 1|2.

Steps followed:

1. I started by installing Apache Maven 4.0.0-rc-4 locally.
2. Used the built in upgrade tool (mvnup) to make the initial changes with mvnup apply --model-version 4.1.0 --all
3. Removed as much explicit sub-module definitions as possible. Only two were really necessary because of the nested archetype modules.
4. Followed the new conventions for parent inference.
5. Built with Maven 4 and reviewed the generated targets including the new consumer POMs.

[mvolikas]

In some POMs we're using tabs for indentation, while in others we have double spaces. Should we agree on a common style and update them?

[rzo1]

Thx. Can we update the action to run with an actual Maven 4 binary? Most likely other ASF projects are doing it similar or https://github.com/s4u/setup-maven-action?tab=readme-ov-file or alike are already Maven 4 ready?

I have no preference regarding formatting.

[mvolikas]

In RC 5, you can no longer have submodules together with jar packaging, so I updated accordingly.

[mvolikas]

This was the easiest way I found to build with specific maven 4 versions. @rzo1 I think that the GitHub action you shared didn't work due to ASF restrictions on action repositories.

[rzo1]

Looks good. I think we can make progress with the PR once Maven 4 is officially released, but the PR shows, that we are ready for it.

Alterantive would be to start a discussion on dev@, if we want to switch to Maven 4 RC's for building SC. WDYT?

[rzo1]

In some POMs we're using tabs for indentation, while in others we have double spaces. Should we agree on a common style and update them?

I am fine with it. I think we have checkstyle enabled, so maybe something for it to cover?