Update Wicket Text Field on onUpdate event

I have a component that extends TextField where a user can type an web address. I want that after the user type something (for example www.example.org) to change that value to something else (for exemple http://www.example.org)

I have tried this:

urlField = new TextFieldIndicatingError<String>("url", new PropertyModel<String>(this, "url"));
urlField.add(new AjaxFormComponentUpdatingBehavior("onblur") {
                     @Override
                     protected void onUpdate(AjaxRequestTarget target) 
                     {
                         //url = "ABCDDEE";
                         urlField.getModel().setObject("AAAA");
                     }
                 });

but anything inside the onUpdate() doesn't seems to have an effect in the TextField's value. What I'm doing wrong here?

You need to use target.add(urlField) to update it on the client side after setting its new model.