printUsers(service.getUsers());
System.out.println("Asking the service to add a new user " + user + " and also say hi");
System.out.println(service.sayHi(user));
System.out.println(service.sayHiToUser(new UserImpl(user)));
System.out.println("Getting the list of existing users");
Map<Integer, User> users = service.getUsers();
printUsers(users);