Implement a way to retrieve users and groups for a group

    	UserManager userManager = nuxeoClient.getUserManager();
    	// create group
    	Group group = new Group();
    	group.setGroupName(groupName);
    	group.setGroupLabel(groupName);
    	Group nuxeoGroup = userManager.createGroup(group);
    	System.out.println("Group " + nuxeoGroup.getGroupName() + " created");
    	// create user
    	User newUser = new User();
    	newUser.setUserName(userName);
    	newUser.setCompany("Nuxeo");
    	newUser.setEmail(userName + "@nuxeo.com");
    	newUser.setFirstName("to");
    	newUser.setLastName("to");
    	newUser.setPassword(userName);
    	User userObj = userManager.createUser(newUser);
    	System.out.println("User " + userObj.getUserName() + " created");
    	// add user to group
    	User user = userManager.addUserToGroup(userName, groupName);
    	System.out.println("User " + user.getUserName() + " added to group " + groupName);
    	// fetch group
    	Group fetchedGroup = userManager.fetchGroup(groupName);
    	System.out.println("Fetch group members of group " + fetchedGroup.getGroupName() + ": " + fetchedGroup.getMemberUsers());