Vaadin14(流)-绑定-在哪里可以访问.setAsRequired(布尔值)

import com.vaadin.flow.component.button.Button;
import com.vaadin.flow.component.formlayout.FormLayout;
import com.vaadin.flow.component.orderedlayout.VerticalLayout;
import com.vaadin.flow.component.textfield.TextField;
import com.vaadin.flow.data.binder.Binder;
import com.vaadin.flow.router.Route;

@Route("")
public class MainView extends VerticalLayout {

    private TextField name = new TextField("Name");
    private Button save = new Button("Save");

    public MainView() {
        FormLayout form = new FormLayout();
        form.add(name);

        Binder<Person> binder = new Binder<>(Person.class);
        binder.forField(name).bind(Person::getName, Person::setName);
        binder.forField(name).setAsRequired(true); // 设置为必填项

        save.addClickListener(event -> {
            if (binder.validate().isOk()) {
                // 保存数据
            } else {
                // 显示错误信息
            }
        });

        form.add(save);
        add(form);
    }

    public static class Person {
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}