title: Java - docx4j-ImportXHTML : issue with NamespacePrefixMapper not found
body: <p>I want to convert html content to docx.</p>
  
  <p>I am using docx4j-ImportXHTML and docx4j.</p>
  
  <pre><code>String xhtml= "&lt;div&gt;hello world &lt;bold&gt;bold character&lt;/bold&gt;&lt;/div&gt;";
  
  WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.createPackage();
  XHTMLImporterImpl XHTMLImporter = new XHTMLImporterImpl(wordMLPackage);
  
  
  wordMLPackage.getMainDocumentPart().getContent().addAll(
              XHTMLImporter.convert( xhtml, null) );
  
  System.out.println(XmlUtils.marshaltoString(wordMLPackage.getMainDocumentPart().getJaxbElement(), true, true));
  
  wordMLPackage.save(new java.io.File("/home/out.docx") );
  </code></pre>
  
  <p>I am getting this exception when I call convert method : </p>
  
  <blockquote>
    <p>java.lang.RuntimeException: javax.xml.bind.JAXBException: Can't create
    internal NamespacePrefixMapper
     - with linked exception: [java.lang.ClassNotFoundException: org.docx4j.jaxb.suninternal.NamespacePrefixMapper]   at
    org.docx4j.XmlUtils.marshaltoString(XmlUtils.java:840)    at
    org.docx4j.XmlUtils.marshaltoString(XmlUtils.java:716)    at
    org.docx4j.model.styles.StyleTree.createVirtualStylesForDocDefaults(StyleTree.java:487)
      at org.docx4j.model.styles.StyleTree.(StyleTree.java:107)     at
    org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart.getStyleTree(MainDocumentPart.java:202)
      at
    org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart.getStyleTree(MainDocumentPart.java:172)
      at
    org.docx4j.convert.in.xhtml.XHTMLImporterImpl.stylesToCSS(XHTMLImporterImpl.java:464)
      at
    org.docx4j.convert.in.xhtml.XHTMLImporterImpl.getRenderer(XHTMLImporterImpl.java:271)
      at
    org.docx4j.convert.in.xhtml.XHTMLImporterImpl.convert(XHTMLImporterImpl.java:663)</p>
  </blockquote>