如何使用JAXB为XML中的空元素生成自结束标记< tag />

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Tag {
    private String value;

    @XmlElement(nillable = true)
    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }
}

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import java.io.StringWriter;

public class Main {
    public static void main(String[] args) {
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(Tag.class);
            Marshaller marshaller = jaxbContext.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            Tag tag = new Tag();
            tag.setValue(null); // 设置为空元素

            StringWriter writer = new StringWriter();
            marshaller.marshal(tag, writer);

            String xml = writer.toString();
            System.out.println(xml);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<tag xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>