code: public void warn(SourceLocator srcLctr, String msg, Object[] args) throws TransformerException
    {
      warn(srcLctr, null, null, msg, args);
    }
docs: Warn the user of a problem.
  
  @param msg Message text to issue
  @param args Arguments to pass to the message
  @throws XSLProcessorException thrown if the active ProblemListener and XPathContext decide
  the error condition is severe enough to halt processing.
  
  @throws TransformerException
  @xsl.usage internal