Java EE (Java Enterprise Edition) General Discussion

I would like to understand why the following code return a correct Document instance if it running under jdk 1.4.2 and instead return null if it running under jdk 1.5.0.

Thanks!
F.

import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

String test = "<root>" + "" + "</root>";
StringReader sreader = new StringReader (test);
InputSource is = new InputSource(sreader);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
builder = factory.newDocumentBuilder();
 
Document doc =  builder.parse(is);
 
System.out.println("Document is: " + doc);