//now we have a shareable node N with path a1/b1
Session session = testRootNode.getSession();
Workspace workspace = session.getWorkspace();
String path = a2.getPath() + "/b2";
workspace.clone(workspace.getName(), b1.getPath(), path, false);
//now we have another shareable node N' in the same shared set as N with path a1/a2/b2
//using the path a1/a2/b2, we should get the node N' here
Item item = session.getItem(path);