Grid setColumns not working in second tab

Vaadin 6 / 7 / 8 Framework Data Binding
1

Hi guys,

following situation:
i have two classes like:

public class User {
     long id;
     Address address;
}

public class Address {
     String firstName;
}

And then:

Grid grid = new Grid(User.class);

grid.setColumns("id", "address.firstName");

Problem:

if i start the app, it works, it shows the grid with 2 columns (ID and first name). but if i open the application a second time in another tab i get exception:

could not resolve property name 'firstName' from Property set from bean user

but “firstName” is not in user, but in user.address. what am i doing wrong? or is it vaadin-bug?

Thank