setting package on new Java objects

I have a wizard in which I create some Java files. It used to be that
the package could be computed easily from the path to the root of the
mountpoint. Now the path I get is relative to the root. So I end up
with files with package declarations like

package /home/pswisnov/Projects/webmod/src/ws;

I'm trying to figure out if there is an encapsulated way to do
this. There seems to be an implementation in JavaWizardData.setTarget
which I can copy over, but is there or could there be an entry point
provided by the Java module for computing the package name from a
project member? 

Thanks,

Peter