get user groups members using Google Directory API

Question

I'm using the Google Directory API, here is the code that I'm using and I get the user info. But I need to get also the groups that the user is member.

My question is how can I do that when I have the user. I have another code to get the members, from a group but this impractical, because if I do that. I'll will need to get all the members for all the groups.

public static void get_user(String correo) {
    Users us;


    try {
        service = getDirectoryService("admin@domain.mx");
        try {
            us = service.users().list().setCustomer("my_customer").setQuery("email:"+correo).execute();
            System.out.println("us:"+us);

            List<User> lu = us.getUsers();
            System.out.println("lu:"+lu);
            if (lu!=null) {
                System.out.println("reses:"+lu.size());
                for (int i=0;i<lu.size();i++) {
                    User u  = lu.get(i);
                    String id = u.getId();
                    String pemail = u.getPrimaryEmail();
                    UserName username = u.getName();

                    System.out.println("xxxx.................");
                    System.out.println(i+":"+id);
                    System.out.println("username:"+username.getFullName());
                    System.out.println("full:"+username.getGivenName());
                    System.out.println("email:"+pemail);
                    System.out.println("organization unit:"+u.getOrgUnitPath());

                }
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    } catch (GeneralSecurityException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (URISyntaxException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

}