Only let certain classes construct an object

I have to write a test for the login dialog that shows up on my website, but there are two, and only two access points for this login dialog. Ideally, my page objects should reflect the restricted access to this login dialog.

1. When you clickLogin on the Header, a LoginDialog pops up

2. When you postComment on an Article, and you aren't logged in, a LoginDialog pops up.

Here's what it looks like in code:

new LoginDialog().login();          // shouldn't be allowed
new Header().clickLogin().login();  // should be allowed
new Article().postComment().login() // should be allowed

However, I had some trouble coming up with a sensible method for allowing only Header and Article to initialize a LoginDialog.

What I ended up using seems pretty esoteric, so I'll try my best to explain it. Essentially, LoginDialog only has two constructors, which both take in an object that can only be constructed in either Header or Article.

public class Main {
  public static void main(String [] args) {
    new Header().clickLogin().login();
    logout();
    new Article().postComment().login();
  }
}   

public class LoginDialog {
  public LoginDialog(Article._ article) {
  }

  public LoginDialog(Header._ header) {
  }

  public void login() {
    System.out.println("Logged in!");
  }
}

public class Article {
  public class _ {
    private _() {
    }
  }

  public LoginDialog postComment() {
    if (!loggedIn()) {
      return new LoginDialog(new _());
    } else {
      return null;
    }
  }
}

public class Header {
  public class _{
    private _() {
    }
  }

  public LoginDialog clickLogin() {
    if (!loggedIn()) {
      return new LoginDialog(new _());
    } else {
      return null;
    }
  }
}

To be honest, I'm not quite sure of what my question is. I guess I want to know whether or not this is a pattern that's been used elsewhere, and if it is, what is its name? Otherwise, is there a better way to accomplish what I want?