Spring MVC binding

I have the following command object:

public class User {
    private Department department;
    private String firstName;
    private String lastName;
    private String login;
    private String password;
...
}

which should be rendered at jsp page:

So when I submit with empty department.name and department.description the Spring auto-instantiate object Department with empty properties. (See https://jira.springframework.org/browse/SPR-6032 I would keep autoGrowNestedPaths=true)

What is need to do for getting back User object where Department object=null?