You're not going to like this!

Support for maven2 aggregator plugins.

e.g.

root
+ pom.xml
+ child1
+ pom.xml
+ child2
+ pom.xml
+ subproj
+ pom.xml
+ child3
+ pom.xml
+ child4
+ pom.xml

If root/pom.xml includes a plugin that attaches an aggregator goal to a phase,
the aggregator may not function as intended:

• maven2 projects effectively invoke each module as mvn -N
• thus each module is built independently of the others
• thus each module does not have the context of the other builds
• this is why to get the separate modules to use the other modules that have
  just been build, hudson requires mvn install and not mvn package. with mvn
  package, the build artifacts should be retained in the maven context and used in
  preference to the repository. Because each module is in it's own context, we
  require mvn install.
• thus the aggregator plugin running in pom.xml will not see any of the
  artifacts from the child projects.

The only way I see around this at the moment is to fall back to the standard
freestyle project.