Misleading warning when creating a Maven plugin defining a custom packaging

When creating a custom packaging using the 2.4.1 version of the maven-plugin-plugin, I'm getting the following warning message:

[INFO] Building foobar-maven-plugin
[INFO] task-segment: [install]
[INFO] ------------------------------------------------------------------------
[INFO] [plugin:descriptor]
[INFO] Using 2 extractors.
[INFO] Applying extractor for language: java
[INFO] Extractor for language: java found 0 mojo descriptors.
[INFO] Applying extractor for language: bsh
[INFO] Extractor for language: bsh found 0 mojo descriptors.
[WARNING]
[WARNING]
[WARNING] *******************************************************
[WARNING] Deprecation Alert:
[WARNING] No mojo descriptors were found in this project which has a packaging type of maven-plugin.
[WARNING] In future versions of the plugin tools, this will fail the build.
[WARNING] If this project is an archetype, change the packaging type from maven-plugin to maven-archetype.
[WARNING] ********************************************************

Indeed, my project contains no Mojos, only a plexus components.xml file. Now if you try to enforce a rule that says that a maven-plugin must contain at least one Mojo (see MPLUGIN-106), that's fine, but which packaging am I supposed to use to create a plugin that defines a new packaging (here, the foobar packaging)