public static XmlElementDescriptor getRelaxedDescriptor(XmlElementDescriptor base, final XmlTag childTag) {
    final String namespace = childTag.getNamespace();
    final XmlExtension extension = XmlExtension.getExtensionByElement(childTag);
    if(!XmlUtil.XHTML_URI.equals(namespace) &&
       ( base.getContentType() != XmlElementDescriptor.CONTENT_TYPE_EMPTY ||
         (extension != null && extension.isCustomTagAllowed(childTag)) // allow custom tag
       ) ) {
      return new AnyXmlElementDescriptor(base,childTag.getNSDescriptor(namespace,true));
    }
    return null;
  }
public static XmlElementDescriptor getRelaxedDescriptor(XmlElementDescriptor base, final XmlTag childTag)