code: private void handleArgNice(final Deque<String> args) {
          final String value = args.pop();
          if (value == null) {
              throw new BuildException("You must supply a niceness value (1-10) after the --nice option");
          }
          try {
              threadPriority = Integer.decode(value);
          } catch (final NumberFormatException e) {
              throw new BuildException("Unrecognized niceness value: " + value);
          }
  
          if (threadPriority < Thread.MIN_PRIORITY || threadPriority > Thread.MAX_PRIORITY) {
              throw new BuildException("Niceness value is out of the range 1-10");
          }
      }
docs: Handle the --nice argument.