[MNG-8494] Restore Maven 3 compatibility

[jira-importer]

Guillaume Nodet opened MNG-8494 and commented

The Maven 3 modules have been moved into the /compat/ directory.
But before this happened and the new Maven 4 API was introduced, those classes undergo quite some incompatible changes. Given they are now deprecated, it would make sense to restore them to full Maven 3.9.x compatibility.

---

Issue Links:

• MNG-7266 Remove maven-compat module

• MNG-8371 Document Deprecation

• MNG-6561 New RepositorySystem implementation as replacement of deprecated from maven-compat

• MPIR-475 Drop usage of maven-artifact-transfer

• MSITE-833 Remove dependency to maven-compat

• MPLUGINTESTING-70 maven-compat requirement

Remote Links:

• GitHub Pull Request #2031
  

Backported to: 4.0.0-rc-3

[jira-importer]

Sylwester Lachiewicz commented

Maybe there is a way to completely lose it somewhere maven-compat for 3.x ? Any reason why something needs it in Maven 3.x world? I believe that some parts of maven-plugin-testing may have dependencies - but what else?

[jira-importer]

Guillaume Nodet commented

The maven-compat is required at runtime when building sites for example. Maven itself does not use it.

I once had a goal to remove maven-compat completely, but that's not on my radar anymore.

Here again, I think switching plugins to the new API will solve the problem automatically, so not sure it's worth pursuing. I'd rather switch them directly to the new Maven API. Maven 5 should drop Maven 3 compatibility and all /compat/maven-* artifacts imho. Maven 4 currently keeps some level of compatibility with Maven 3 and Maven 2...

[jira-importer]

Sylwester Lachiewicz commented

Moving to API 4 could be done if we have docs on "what and how" to move from API 3 and all deprecated stuff.

[jira-importer]

Guillaume Nodet commented

Sylwester Lachiewicz you mean for plugins ?

The rules are quite simple

• the plugin can only depend on org.apache.maven:maven-api-* artifacts (no any other maven related artifacts) at compile time
• avoid plexus artifacts at compile time
• mojo annotations are now in org.apache.maven.api.plugin.annotations package
• injection annotations come from org.apache.maven.api.di
• replace MavenSession with org.apache.maven.api.Session, MavenProject with org.apache.maven.api.Project, classes from org.apache.maven.model with their counterparts from org.apache.maven.api.model
• unit test needs JUnit 5 and need the org.apache.maven.api.plugin.testing

[jira-importer]

Guillaume Nodet commented

I started a page, I'll continue updating it in the coming days:
https://gist.github.com/gnodet/68ed6d5ef589d6cd84f73c68f5f6092b