[MRESOLVER-390] Customize graph visiting strategy

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0-alpha-1, 2.0.0
• Component/s: Resolver
• Assignee: Tamas Cservenak
• Reporter: Tamas Cservenak
• Created: 27/Jul/23 09:28
• Updated: 02/Nov/23 11:07
• Resolved: 13/Oct/23 23:50

Description

The classpath built by Maven seems off, see MNG-6357 and there is even a reproducer.

Reason is simple: we use DF derivatives to create classpath.

Fix: Resolver (and thus Maven) had "wired in" strategy to flatten dependency graph into list, and it was always "preOrder", while there existed alternate solutions like "postOrder". This PR introduces "levelOrder" as asked by users, and also makes it configurable (via session config) which strategy should be used, and exposes helper classes and methods.

Now session can be configured to use following strategies to flatten the graph:

• "preOrder" – as before
• "postOrder" – was already present
• "levelOrder" – as asked by users, artifact list is ordered by their depth (distance from root)

By default, this PR introduces NO behavior changes, but opens configuration that does allow to alter these.

Issue Links

• links to: GitHub Pull Request #322