class PollingConfig extends WatchServiceConfiguration {

    private final long interval;
    private final TimeUnit timeUnit;

    private PollingConfig(long interval, TimeUnit timeUnit) {
      checkArgument(interval > 0, "interval (%s) must be positive", interval);
      this.interval = interval;
      this.timeUnit = checkNotNull(timeUnit);
    }

    @Override
    AbstractWatchService newWatchService(FileSystemView view, PathService pathService) {
      return new PollingWatchService(view, pathService, view.state(), interval, timeUnit);
    }

    @Override
    public String toString() {<FILL_FUNCTION_BODY>}
  }

      return "WatchServiceConfiguration.polling(" + interval + ", " + timeUnit + ")";
    
<no_super_class>