code: public void warning(final String msg)
      {
          warnings++;
  
          if (!suppressOutput)
          {
              out.println("WARNING: " + msg);
          }
  
          if (warningsFatal && stopOnError)
          {
              throw new IllegalArgumentException(msg);
          }
      }
docs: Record a message signifying an warning condition.
  
  @param msg signifying an warning.