[MNG-7344] track dependencyManagement import location in effective Model for MPH-183

[jjkester]

The goal of MPH-183 is to print via which BOM(s) a dependencyManagement dependency got in the effective POM in case of dependencyManagement import. MNG-7344 implements the required tracking in Maven core effective model.

This information was previously not available to the help plugin. This MR:

• introduces a change to the InputSource model to keep a hierarchy of sources (which are POM files) by tracking the POM that imported it
• tracks dependencies through different dependency management imports, setting the hierarchy of sources on the InputSource objects

For now, this code has been written under the assumption that a BOM hierarchy (at least at the point the dependency management blocks are imported) is tree-shaped, without diamonds. That is, given a project P with dependency D, importing BOMs A and B, BOM C with dependency D, only A or B (not both) can import C.

• [ ] Check assumption

If such a structure would be possible, the end result may be incorrectly represented as C via B via A, which is not correct, because there is no direct relationship between A and B.

Furthermore, at the moment the original InputSource of the file is mutated. This makes the hierarchy valid for all imported dependencies, and potentially other parts of the effective POM. This may not be desirable. A relatively minor change, replacing InputSource objects that are about to be mutated, would solve this issue. In case updating the original InputSource is desirable, there may be a better place to set it.

• [ ] Check solution strategy

Any input on the above points is highly appreciated.

A pull request for printing this information in the effective POM: https://github.com/apache/maven-help-plugin/pull/37

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[jjkester]

Hey @rfscholte, would it be appropriate to create a new ticket for this? The ticket this work is under is focused on maven-help-plugin, but this is turning out a bit more involved. I'm happy to work on it, but I think it makes sense to make the requirements, reasoning and discussion easily findable at a location where it is expected.

If you agree, can you create a ticket and formulate your ideas and expected results?

[rfscholte]

I've created https://issues.apache.org/jira/browse/MNG-7344