code: public MessageResourcesModel getDefaultMessageResources()
      {
          for ( java.util.Iterator ii = _messageResources.iterator(); ii.hasNext(); )  
          {
              MessageResourcesModel i = ( MessageResourcesModel ) ii.next();
              if ( i.getKey() == null ) return i;
          }
          
          return null;
      }
docs: Get the MessageResourcesModel for which no "key" is set (the default one used at runtime).