code: public static boolean isSortedDescending(SortModel sortModel, String sortExpression) {
          if(sortModel == null || sortExpression == null)
              return false;
  
          Sort sort = sortModel.lookupSort(sortExpression);
          if(sort != null && sort.getDirection() == SortDirection.DESCENDING)
              return true;
          else return false;
      }
docs: Given a sort expression, check to see if the sort expression is sorted descending in a data grid's
  {@link SortModel}.
  @param sortModel a grid's sort model
  @param sortExpression the sort expression
  @return return <code>true</code> if a {@link Sort} is found whose sort expression
  matches the sort expression given here and whose direction is {@link SortDirection#DESCENDING}.
  @netui:jspfunction name="isSortedDescending"
  signature="boolean isSortedDescending(org.apache.beehive.netui.databinding.datagrid.api.sort.SortModel,java.lang.String)"