// "Make sure you are not calling Component#getString() inside your Component's constructor."
add(new TextField("address"));
add(new RequiredTextField("city").add(new RequiredBehavior()));
add(new RequiredTextField("province").add(new RequiredBehavior()));
add(new RequiredTextField("postalCode").add(new RequiredBehavior()));
SimpleCountryDropDownChoice countries = new SimpleCountryDropDownChoice("country",
new PropertyModel<String>(getDefaultModel(), "country"));
add(countries.setRequired(true).add(new RequiredBehavior()));
}