Rebind data in form build with @PropertyId doesn't work.

Vaadin 6 / 7 / 8 Framework Data Binding
1

Hello, I have problem with rebind data in form build with @PropertyId. When I do fieldgroup.setItemDataSource( item ) data aren’t changing. I my code I hava my own form:


    class UserForm extends FormLayout
    {
        @PropertyId( "username" )
        TextField tfUserName = new TextField( "Username" );
        
        @PropertyId( "firstname" )
        TextField tfFirstName = new TextField( "Firstname" );
        
        UserForm()
        {            
            addComponent( tfUserName );
            addComponent( tfFirstName );
        }        
    }

And I use this form on that way:


    UserForm formUser = new UserForm();
    FieldGroup fieldGroup = new FieldGroup();
    fieldGroup.bindMemberFields( formUser );

When Item is change I do :


    fieldGroup.setItemDataSource( item )

but the data in the form does not displayed. I found a similar case on url=https://vaadin.com/tutorial] vaadin tutorial
[/url]. I change the part with build form and everything was fine. Does this mean that the forms with @PropertyId can not be used in this way?