Use bomDeps when importing Maven projects

[alexarchambault]

This tries to take into account "import" dependencies when importing Maven projects (which correspond to bomModulesDeps and bomIvyDeps in Mill), and adds parent modules there too (parent modules are basically BOMs).

Checking if this breaks the current tests. Extra tests might need to be added, to test these changes.

[alexarchambault]

CI error looks like a flake

[lihaoyi]

Lemme kick the CI and see if it turns green

[lihaoyi]

@alexarchambault seems the test is failing reliably on CI, does it pass on your machine?

[alexarchambault]

@alexarchambault seems the test is failing reliably on CI, does it pass on your machine?

My bad, I misread the CI output. It fails on my machine too, yes.

[alexarchambault]

So adding the parent POM to bomDeps during Maven imports is a problem. bomDeps can only be external BOMs, fetched from a Maven repository. If the parent is a module of the project being imported, then it's not found on Maven repos, and the generated Mill build fails.

This needs a missing part of BOM support, something like BomModule, where the dependency management defined in the Maven parent module would be written to (in JavaModule#depManagement), that other modules could refer to via a new bomModules say (like bomDeps, but for local modules), and that would get published as a BOM (no sources / no JAR, pom artifact type with dependencyManagement section).

[alexarchambault]

The failing example is this one. It runs into the parent POM issue above if we add bomDeps for parent POMs to it.

[lihaoyi]

@alexarchambault perhaps bomDeps should be named bomIvyDeps, and then have a separate bomModuleDeps to refer to local modules? That would follow the naming convention we use elsewhere in JavaModule

[alexarchambault]

About this PR: it tries to set JavaModule#{bomModuleDeps,bomIvyDeps} in a sensible way when importing Maven projects. It seems it doesn't break the current tests, but I didn't try it on actual Maven projects that need those tasks. So I'm not sure if it should be merged right now.

But if any one ran into issues with empty versions or faulty class paths, when importing Maven projects, this might help.