我创建了一个扩展 Exception 类的类，我在 Eclipse 上收到了这个警告

The serializable class PhoneAlreadyExists does not declare a static final serialVersionUID field of type long

请问如何删除它？

public class PhoneAlreadyExists extends Exception {
    public PhoneAlreadyExists() {
        // TODO Auto-generated constructor stub
        super();
    }

    PhoneAlreadyExists(String message) {
        super(message);
    }

}