PackageBuilderShellMojo (m2) and classloaders

[David Jencks]

Jason Dillon asked last night on IRC why the PackgeBuilderShellMojo  
for the m2 packaging plugin used reflection to create the  
PackageBuilder.  We need to control the classloader for  
PackageBuilder pretty closely so it has the same classpath as j2ee- 
system.  In maven 1, IIUC, plugins get instantiated using a child  
classloader of the project calling the plugin: this classloader  
typically has a more or less random selection of large numbers of  
geronimo jars in it, far more than j2ee-system, and in particular  
including all the classes for the dependencies of the module/ 
configuration you are trying to build.  The only solution I could see  
for m1 was to construct a classloader myself and load PackageBuilder  
in my own classloader and access the instance by reflection.

I believe the situation is better in m2 and that the plugin is  
instantiated using a classloader determined solely by the plugin's  
pom.  If so, we should be safe in eliminating this extra reflection  
code and in fact using PackageBuilder directly without the "shell".   
If not, we should keep using the inconvenient reflection code.

thanks
david jencks