code: @SuppressWarnings({ "unchecked", "rawtypes" })
  	protected Form<?> newForm(final String id,
  		final IModel<? extends BaseUsernameSignUpModel> model)
  	{
  		return new Form(id, model);
  	}
docs: Factory method for creating the Form. This method is invoked in the constructor from the
  derived classes and can be overridden so users can provide their own version of a Form.
  
  @param id
  the id
  @param model
  the model
  @return the form