Java odftoolkit, how to add node created from plain string into odf document

I have a code:

// -----------------------------------------------------------------

TextDocument resDoc = TextDocument.loadDocument( someInputStream );

Section section = resDoc.getSectionByName( "Section1" );  // this section does exist in the document

// create new node form String

String fragment = "<text:p text:style-name=\"P13\"><text:span text:style-name=\"T1\">Test</text:span></text:p>";

Node node = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse( new InputSource( new StringReader( fragment ) ) ).getDocumentElement();
node = section.getOdfElement().getOwnerDocument().importNode( node, true );

// append new node into section

section.getOdfElement().appendChild( node );

// -----------------------------------------------------------------

The code runs without a problem. But nothing does appear in the section in the result document. Please any idea how can I add new nodes created from string into the odf document?

I've got a solution from Svante Schubert from odf-users mailing group:

The trick is to make the DocumentFactory namespace-aware and in addition, add a namespace to your text snippet. In detail this is being changed:

OLD:

String fragment = "<text:p text:style-name=\"P13\"><text:span text:style-name=\"T1\">Test</text:span></text:p>";
Node node = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new

InputSource(new StringReader(fragment ))).getDocumentElement();

NEW:

String fragment = "<text:p xmlns:text=\"urn:oasis:names:tc:opendocument:xmlns:text:1.0\" text:style-name=\"P13\"><text:span text:style-name=\"T1\">Test</text:span></text:p>";
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);

So based on his finding I came up with a method:

private Node importNodeFromString( String fragment, Document ownerDokument ) {
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    dbf.setNamespaceAware( true );

    Node node;
    try {
        node = dbf.newDocumentBuilder().parse( new InputSource( new StringReader( fragment ) ) ).getDocumentElement();
    }
    catch ( SAXException | IOException | ParserConfigurationException e )                {
        throw new RuntimeException( e );
    }

    node = ownerDokument.importNode( node, true );
    return node;
}

That can be used as:

section.getOdfElement().appendChild(importNodeFromString(fragmment, section.getOdfElement().getOwnerDocument()))