// Visit the rest of the SELECT statement, including its upstream
// sources (e.g., nested SELECT statements).
s.getSource().accept(this);
GroupBy groupBy = s.getGroupBy();
if (null != groupBy) {
groupBy.accept(this);
}
List<WindowDef> windowDefs = s.getWindowDefs();
if (null != windowDefs) {
for (WindowDef def : windowDefs) {