the dependency graph module is only used to render the dependency tree on the artifact information pages. It currently reproduces a lot of Maven functionality, and is heavily tied to the archiva-repository-layer and archiva-model.
We should instead use the standard Maven library for handling Maven dependency trees. If we later encounter different types of trees, we can provide alternative implementations. It's unlikely something as generic is needed (though the code is still there to be revisited in SVN if the case arises)