invokevirtual

 public RandomListNode copyRandomList(RandomListNode node) {
        return copyHelper(node, new HashMap<>());
    }

    public static RandomListNode copyHelper(RandomListNode head, Map<Integer, RandomListNode> hm) {
        if (head == null) {
            return null;
        }
        if (hm.containsKey(head.label)) {
            return hm.get(head.label);
        }
        RandomListNode node = new RandomListNode(head.label);
        hm.put(node.label, node);
        node.next = copyHelper(head.next, hm);
        node.random = copyHelper(head.random, hm);
        return node;
    }