jdom 写出 xml空标签的 开始结束标签,该怎么解决

import java.io.*;
import org.jdom.*;
import org.jdom.output.XMLOutputter;

public class DomTest {

    public void Create() {
        try {
            Document doc = new Document();

            Element root = new Element("root");
            doc.setRootElement(root);
            Element el1 = new Element("elment1");        
            Element el2 = new Element("element2").addContent("");

            root.addContent(el1);
            root.addContent(el2);

            XMLOutputter outputter = new XMLOutputter();
            outputter.output(doc, new FileWriter("test.xml"));
        } catch (Exception e) {
            System.out.println(e);
        }
    }

    public static void main(String args[]) {
        new DomTest().Create();
    }
}