code: public XMLFilter newXMLFilter(Source src)
            throws TransformerConfigurationException
    {
  
      Templates templates = newTemplates(src);
      if( templates==null ) return null;
      
      return newXMLFilter(templates);
    }
docs: Create an XMLFilter that uses the given source as the
  transformation instructions.
  
  @param src The source of the transformation instructions.
  
  @return An XMLFilter object, or null if this feature is not supported.
  
  @throws TransformerConfigurationException