code: public InputSource resolveEntity(
            StylesheetHandler handler, String publicId, String systemId)
              throws org.xml.sax.SAXException
    {
      return null;
    }
docs: Resolve an external entity.
  
  
  @param handler non-null reference to current StylesheetHandler that is constructing the Templates.
  @param publicId The public identifer, or null if none is
  available.
  @param systemId The system identifier provided in the XML
  document.
  @return The new input source, or null to require the
  default behaviour.