MNG-7401 - Make MavenSession#getCurrentProject() using a thread local

[laeubi]

This allows multiple threads to set/get the current project on the same session object while still having clones maintain there own state.

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[michael-o]

We previously has serious regressions with thread locals, I don't know whether this is a good idea. @gnodet

[michael-o]

@famod

[laeubi]

We previously has serious regressions with thread locals, I don't know whether this is a good idea. @gnodet

I have found some places where the active data was not reset and that might be the cause for such issues. I think I'll update the PR to create a new thread local, than this would be backward compatible and one could change the code accordingly afterwards.

[rmannibucau]

+1 to fix instance lifecycle and not use any threadlocal which got proven brekaing plugins too much

[laeubi]

+1 to fix instance lifecycle and not use any threadlocal which got proven brekaing plugins too much

What do you mean here in particular? I think it is quite clear to me now what would be the issue with my inital approach thanks to @michael-o and I'm about to fix that. Passing the Session all along seems to break the idea of DI...

[laeubi]

I have adjusted the PR let me know what you think.

[laeubi]

The only issue that can arise now is that I set the current project and pass the session to another thread without cloning it, but that should be illegal/broken already before isn't it?

[laeubi]

One workaround seems to use the LegacySupport class to access the session instead of injecting it...

[jira-importer]

Resolve #9168