Unwanted Dom4J Namespace

When creating a document with a default namespace <root xmlns="....">using DOM4J, I get the following output on writing to file.

<?xml version="1.0" encoding="UTF-8"?>

<root xmlns="http:/foo.bar">
  <foo xmlns="">bar</foo> <!-- unwanted xmlns="" on foo -->
</root>

What I expected (and want) is for foo to be <foo> not <foo xmlns="">. Here is some demo code

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

public class App {

    public static void main(String[] args) throws Exception {
        Namespace xmlns = DocumentHelper.createNamespace("", "http:/foo.bar");
        Element root = DocumentHelper.createElement("root");
        root.add(xmlns);

        Document document = DocumentHelper.createDocument();
        document.setRootElement(root);

        Element child = DocumentHelper.createElement("foo");
        child.setText("bar");
        root.add(child);

        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter writer = new XMLWriter( System.out, format );
        writer.write( document );
    }
}

How do I remove the extra attribute from <foo>? I'm happy to use a different library if that would be easier.

SOLUTION

The answer below together with this question helped solve my issue. I have also included the corrected code below:

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

public class App {

    public static void main(String[] args) throws Exception {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement("root");

        Namespace xmlns = Namespace.get("http:/foo.bar");
        root.add(xmlns);

        root.addElement("foo", "http:/foo.bar")
                .addText("bar");

        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter writer = new XMLWriter( System.out, format );
        writer.write( document );
    }
}