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