有没有一种方法可以让Wicket DropDownChoice提供写入选项？

import org.apache.wicket.markup.html.form.DropDownChoice;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.PropertyModel;

public class WritableDropDownChoice<T> extends DropDownChoice<T> {

    public WritableDropDownChoice(String id, IModel<T> model, List<? extends T> choices) {
        super(id, model, choices);
    }

    @Override
    public void convertInput() {
        String input = getRequest().getRequestParameters().getParameterValue(getInputName()).toString();
        setConvertedInput(getModel().getObject());
        getModel().setObject(convertChoiceIdToObject(input));
    }

    @Override
    protected void onSelectionChanged(T newSelection) {
        super.onSelectionChanged(newSelection);
        getModel().setObject(newSelection);
    }
}