@Override
 public String getToolTipText(final Object element) {
   final RuleSetViewModel ruleSet = toRuleSet(element);
   if (ruleSet.isLocationValid()) {
     return ruleSet.getResolvedPath();
   }
   return getErrorMessage(ruleSet);
 }
 @Override
 protected String getText(final RuleSetViewModel ruleSet) {
   return ruleSet.getLocation();
 }