Clone a graph (Not that easy as it looks) code example

Example: Clone Graph

HashMap<Node, Node> map = new HashMap<>();
public Node cloneGraph(Node node) {
    map.put(node, new Node(node.val, new ArrayList<>()));
 
    for(Node neighbor: node.neighbors){
        if(map.containsKey(neighbor)){
            map.get(node).neighbors.add(map.get(neighbor)); 
        }else{
            map.get(node).neighbors.add(cloneGraph(neighbor));
        }
    }
 
    return map.get(node);
}