@Override
    public String valueOf(FeatureDescriptor featureDescriptor) {
      long tm = featureDescriptor.getLastTimeUsed();
      if (tm <= 0) return FeatureStatisticsBundle.message("feature.statistics.not.applicable");
      return DateFormatUtil.formatBetweenDates(tm, System.currentTimeMillis());
    }
@Override
    public String valueOf(FeatureDescriptor featureDescriptor)