private ModelVersion getSubsystemVersion(PathAddress address) {
   for (PathElement element : address) {
     if (element.getKey().equals(SUBSYSTEM)) {
       return Tools.createModelVersion(versions.get(SUBSYSTEM, element.getValue()));
     }
   }
   throw new IllegalArgumentException("Could not find subsystem version for " + address);
 }
 private ModelVersion getCoreModelVersion() {
   return Tools.createModelVersion(versions.get(Tools.CORE, Tools.STANDALONE));
 }