Java Play 2.5.10 how to inject play-jongo

I've the following model:

public class Users {

    public static PlayJongo jongo = Play.current().injector().instanceOf(PlayJongo.class);

    public static MongoCollection users() {
        return jongo.getCollection("DB.users");
    }
..
..

public static Users authenticate(String email, String password) {
        Users user = users().findOne("{email: #, removed: false}", email).as(Users.class);

        if (user != null) {
            if (HomeController.checkPassword(password, user.password)) {
                return user;
            }
        }

        return null;
    }
..

I use that in my controllers as:

public Result authenticate() {
        DynamicForm requestData = Form.form().bindFromRequest();
        String email = requestData.get("email").trim();
        String password = requestData.get("password").trim();
        Users user = Users.authenticate(email, password);
        if (user == null) {
            flash("danger", "Incorrect email or password.");
            return redirect(routes.HomeController.login());
        }
        session("email", user.getEmail());
        session("role", user.getRole());
        session("fullname", user.getLastname() + " " + user.getFirstname());
        session("id", user.getId().toString());

        return redirect(routes.HomeController.index());
    }

I tried a lot of combination to use injection with play-jongo without result. E.g.

@Inject
public  PlayJongo jongo;

public  MongoCollection users() {
          return jongo.getCollection("DocBox.users");
}

I enter in a loop of static/non-static referenced context errors. If I remove all static declaration, I'm unable to call Users.method. If I try to inject Users to a controller

  public class HomeController extends Controller {

  @Inject
  public Users users;
  .
  .

and try to call a Users method:

   Users user = users.authenticate(email, password);

I receive a org.jongo.marshall.MarshallingException. My brain is definitively goes overheating, someone can explain me how to use Injection with play-jongo?

I solve the problem. Now I've a UsersRepository that contains the methods that operate on the mongo collection (authenticate, addUser, et al.). And a Users object that only contains the actual data fields (firstname, lastname, email, etc.).

After that I can inject UsersRepository into my controller and use that one instance everywhere.

Thanks to Greg Methvin, Tech Lead - Play Framework