protected Tab getTab() throws XavaException {
   if (tab == null) {
     String tabObject =
         Is.emptyString(collection)
             ? "xava_tab"
             : Tab.COLLECTION_PREFIX + Strings.change(collection, ".", "_");
     tab = (Tab) getContext().get(getRequest(), tabObject);
     if (tab.getCollectionView() != null) {
       tab.getCollectionView().refreshCollections();
     }
   }
   return tab;
 }
 public String getColumnName(int c) {
   return labelAsHeader
       ? getMetaProperty(c).getLabel(locale)
       : Strings.change(getMetaProperty(c).getQualifiedName(), ".", "_");
 }