code: public static void reportWarning(String message)
      {
          int[] linep = { 0 };
          String filename = getSourcePositionFromStack(linep);
          Context.reportWarning(message, filename, linep[0], null, 0);
      }
docs: Report a warning using the error reporter for the current thread.
  
  @param message the warning message to report
  @see org.mozilla.javascript.ErrorReporter