Change lifecycle phases for adding sources

[hgschmie]

It seems that addSources and addTestSources are run in the initialize phase ever since
forever. These goals should be run right before compiling the sources / test sources (in the
generate-sources and generate-test-sources phases).

[keeganwitt]

Hi @hgschmie, thank you for the PR! Can you explain what issue is caused by having it in the current phase?

I think the history of the current phase goes back to the original GMaven plugin, which bound to this same phase, as does the Scala Maven Plugin (though not the Clojure Maven Plugin).

I suspect the thinking was that this was needed for IDE integration, but at least for IntelliJ this doesn't appear to be the case.

[hgschmie]

Hi @keeganwitt,

Thanks for getting back so quickly. I have a bunch of projects where I use groovy for unit testing but not in the regular build cycle. So it seems weird to execute e.g. the addTestSources goal when running only mvn compile. I agree that the change is not strictly necessary (and I can always bind them explicitly into other phases) but it feels that within the "spirit" of the maven lifecycle, these goals should be bound to the intended phases and not just at the earliest possible moment.