List<String> propertyNames = grid.getDataModel().getPropertyNames();
int collapseIndex = propertyNames.indexOf(collapseColumn);
if (collapseIndex < 0) throw new RuntimeException("No such column " + collapseColumn);
Element parentTable = findTable(writer.getElement());
List<Node> parentRows = parentTable.find("tbody").getChildren();
boolean isFirst = true;
for (Node parentRowNode : parentRows) {
Element parentRow = (Element) parentRowNode;
List<Node> parentCells = parentRow.getChildren();