Generate excludes for classpath from Maven's source modifications

I'm using Maven's source code modifications to exclude certain
directories from the build. It would be great if this can be generated by your plugin.
My solution may not be perfect, but I would greatly appreciate it if something similar to my contribution would make it into to the plugin.

Here's how I modified "classpath.jelly":

<j:if test="$

">
<maven:makeRelativePath var="srcDir" basedir="$

" path="$

"/>
<j:set var="exluding" value=""/>
<j:forEach var="sm" items="$

">
<j:forEach var="exclude" items="$

">
<j:set var="excluding" value="$

"/>
</j:if>