}
private void processList(List list, Set<String> xPathStrings) {
for (Object ruleElement : list) {
if (ruleElement instanceof Column) {
final Column column = (Column) ruleElement;
processColumn(column, xPathStrings);
} else if (ruleElement instanceof GroupElement) {
final GroupElement groupElement = (GroupElement) ruleElement;
final List children = groupElement.getChildren();
processList(children, xPathStrings);