this.digraph = digraph;
this.globalRepository = globalRepository != null ? new SubsystemRepository(globalRepository) : null;
this.downloader = downloader;
prepare(root);
repository = new BaseRepository(resToSub.keySet());
// Add a heuristic to sort capabilities :
// if a capability comes from a resource which needs to be installed,
// prefer that one over any capabilities from other resources
findMandatory(root);