public void customComparable() {
    MutableGraph<ComparableSubClass> graph =
        GraphBuilder.undirected().nodeOrder(ElementOrder.<ComparableSubClass>natural()).build();

    ComparableSubClass node2 = new ComparableSubClass(2);
    ComparableSubClass node4 = new ComparableSubClass(4);
    ComparableSubClass node6 = new ComparableSubClass(6);
    ComparableSubClass node8 = new ComparableSubClass(8);

    graph.addNode(node4);