how to let DOM4J to generate <name></name> other than <name/>

Dom4jDemo.java

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

import java.io.IOException;
import java.io.StringWriter;


public class Dom4jDemo {
    public static Document createDocument() {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement("root");
        Element category = root.addElement("category");
        Element id = category.addElement("id");
        id.addAttribute("name", "id");
        id.addText("1");

        root.addElement("empty");
        return document;
    }

    public static String xmlToString(Document document) {
        try {
            OutputFormat xmlFormat = new OutputFormat();
            // OutputFormat.createPrettyPrint();
            xmlFormat.setEncoding("UTF-8");
            // If this is true, elements without any child nodes
            // are output as <name></name> instead of <name/>.
            xmlFormat.setExpandEmptyElements(true);


            StringWriter out = new StringWriter();
            XMLWriter xmlWriter = new XMLWriter(out, xmlFormat);
            xmlWriter.write(document);
            xmlWriter.close();

            return out.toString();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * This Demo will output:
     * <?xml version="1.0" encoding="UTF-8"?>
     * <root><category><id name="id">1</id></category><empty></empty></root>
     */
    public static void main(String[] args) {
        System.out.println(xmlToString(createDocument()));
    }
}

    <dependency>
        <groupId>dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>1.6.1</version>
    </dependency>