presto-main/src/main/java/io/prestosql/sql/planner/plan/MarkDistinctNode.java/MarkDistinctNode/replaceChildren
class MarkDistinctNode:    @Override
    public PlanNode replaceChildren(List<PlanNode> newChildren)
    {
        return new MarkDistinctNode(getId(), Iterables.getOnlyElement(newChildren), markerSymbol, distinctSymbols, hashSymbol);
    }