Improve conflict handling of lifecycle mappings

[kwin]

In case two extensions with overlapping lifecycle mapping (like PDE Connector and Sling IDE Tooling in

m2e-core/org.eclipse.m2e.pde.connector/lifecycle-mapping-metadata.xml

Line 39 in 50ed92a

<artifactId>bnd-maven-plugin</artifactId>

and https://github.com/apache/sling-ide-tooling/blob/93bcb69fe7cfad6b68d5caf838a14d3bdf887b92/eclipse/eclipse-m2e-ui/lifecycle-mapping-metadata.xml#L32) are installed only the errors

Conflicting lifecycle mapping (plugin execution "biz.aQute.bnd:bnd-maven-plugin:6.1.0:bnd-process (execution: generate-osgi-metadata, phase: process-classes)"). To enable full functionality, remove the conflicting mapping and run Maven->Update Project Configuration.
Plugin execution not covered by lifecycle configuration: biz.aQute.bnd:bnd-maven-plugin:6.1.0:bnd-process (execution: generate-osgi-metadata, phase: process-classes)

are emitted for projects leveraging plugins which are affected by the conflicting lifecycle mapping and incremental support for that plugin & goal (in this example bnd-process) is completely disabled.

Instead in case of conflicts it should be possible for a user to decide on a per-project level which lifecycle mapping should be used.

[laeubi]

@kwin thanks for your suggestion, do you plan to give it a try and provide a PR for this?

[kwin]

@laeubi Not in the short-term I fear.

[laeubi]

@mickaelistria @HannesWell could you help here? I think this can become important once we release 1.20 as there might also be collisions with the old takari mapping for tycho.

[mickaelistria]

I don't plan to work on this issue. If the solution is to remove the old takari mapping of Tycho, then we can imagine have the m2e-PDE feature adding a negative requirement towards the takari stuff so we at least ensure both cannot be installed together.

[laeubi]

Okay I'll try to take a look at this I think this is crucial for this release as we will otherwise get complains from users and the current behavior is simply not helpful.

[HannesWell]

Okay I'll try to take a look at this I think this is crucial for this release as we will otherwise get complains from users and the current behavior is simply not helpful.

Thank you Christoph! I agree that this is important but I actually didn't have the plan to work on this, so I'm thankful that you take over. If you need somebody to review, please let me know.

[laeubi]

This is how it will look like for a execution phase with duplicate mappings:

This for a duplicate packaging type mapping:

[laeubi]

This then adds for example the following to the workspace metadata:

<?xml version="1.0" encoding="UTF-8"?>
<lifecycleMappingMetadata>
  <lifecycleMappingFilters>
    <lifecycleMappingFilter>
      <symbolicName>org.sonatype.tycho.m2e</symbolicName>
      <versionRange>[0.9.0,)</versionRange>
      <packagingTypes>
        <packagingType>bundle</packagingType>
      </packagingTypes>
    </lifecycleMappingFilter>
  </lifecycleMappingFilters>
</lifecycleMappingMetadata>