if (order instanceof Aggregation){
OrderPath path = ((Aggregation) order).path();
aggsUsedForSorting.add(path.resolveTopmostAggregator(this));
} else if (order instanceof CompoundOrder) {
CompoundOrder compoundOrder = (CompoundOrder) order;
for (Terms.Order orderElement : compoundOrder.orderElements()) {
if (orderElement instanceof Aggregation) {
OrderPath path = ((Aggregation) orderElement).path();
aggsUsedForSorting.add(path.resolveTopmostAggregator(this));
}
}