Customer reported an issue where setting writer.getDomConfig().setParameter("xml-declaration", true); produces no line break after the xml headers.

Expected:
<?xml version="1.0" encoding="UTF-8"?>
<root>
    <item/>
</root>

Actual:
<?xml version="1.0" encoding="UTF-8"?><root> <<<<--- missing line break after header
    </item>
</root>

import java.io.ByteArrayOutputStream;
import java.io.StringWriter;
import java.io.Writer;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.*;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSOutput;
import org.w3c.dom.ls.LSSerializer;

public class TestToStringLS {

    public static void main(final String[] args) {
        try {
            final DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            final DocumentBuilder builder = dbf.newDocumentBuilder();
            final Document doc = builder.newDocument();

            final Element element = doc.createElement("root");
            doc.appendChild(element);

            final Element itemElement = doc.createElement("item");
            element.appendChild(itemElement);
itemElement.appendChild(itemElement.getOwnerDocument().createTextNode(""));

            System.out.println("------------W3C----------");
            writeDocument(doc);
        } catch (final Exception ex) {
            ex.printStackTrace();
        }
    }

    public static final void writeDocument(final Document doc) {
        final ByteArrayOutputStream outStream = new ByteArrayOutputStream();

        DOMImplementationRegistry domRegistry = null;
        try {
            domRegistry = DOMImplementationRegistry.newInstance();
            final DOMImplementationLS impl =
                    (DOMImplementationLS) domRegistry.getDOMImplementation("LS");
            final LSSerializer writer = impl.createLSSerializer();
writer.getDomConfig().setParameter("xml-declaration", true);
            writer.getDomConfig().setParameter("format-pretty-print", true);
            final LSOutput output = impl.createLSOutput();
            output.setEncoding("UTF-8");
            output.setByteStream(outStream);
            writer.write(doc, output);
            final byte[] result = outStream.toByteArray();
            System.out.println(new String(result));
        } catch (final Exception e) {
            System.err.println("ERROR" + e.getMessage());
            e.printStackTrace();
        }
    }

}