Playing with m2-style-project support for plugins I have discovered the
First build of a m2-style-project, the aggregated project action gets added
successfully to the MavenModuleSet.
None of the MavenModules appear to have the individual project action.
The MavenModuleSetBuild and MavenModuleBuild both show the build actions.
Triggering a reload of Hudson picks up the action.