presto-parser/src/main/java/io/prestosql/sql/tree/WindowFrame.java/WindowFrame/getChildren
class WindowFrame:    @Override
    public List<Node> getChildren()
    {
        ImmutableList.Builder<Node> nodes = ImmutableList.builder();
        nodes.add(start);
        end.ifPresent(nodes::add);
        return nodes.build();
    }