code: protected void validateAppinfoElement(Element appinfoElement) throws CmsXmlException {
  
          // create a document to validate
          Document doc = DocumentHelper.createDocument();
          Element root = doc.addElement(APPINFO_APPINFO);
          // attach the default appinfo schema
          root.add(I_CmsXmlSchemaType.XSI_NAMESPACE);
          root.addAttribute(I_CmsXmlSchemaType.XSI_NAMESPACE_ATTRIBUTE_NO_SCHEMA_LOCATION, APPINFO_SCHEMA_SYSTEM_ID);
          // append the content from the appinfo node in the content definition
          root.appendContent(appinfoElement);
          // now validate the document with the default appinfo schema
          CmsXmlUtils.validateXmlStructure(doc, CmsEncoder.ENCODING_UTF_8, new CmsXmlEntityResolver(null));
      }
docs: Validates if the given <code>appinfo</code> element node from the XML content definition schema
  is valid according the the capabilities of this content handler.<p>
  
  @param appinfoElement the <code>appinfo</code> element node to validate
  
  @throws CmsXmlException in case the element validation fails