docs: private static boolean isValidityRange(Date currentTime, Date thisUpdate, Date nextUpdate)
    {
      long tolerableValidity = calculateTolerableVadility(thisUpdate, nextUpdate);
      return thisUpdate.getTime() - MAX_CLOCK_SKEW_IN_MILLISECONDS <= currentTime.getTime() &&
             currentTime.getTime() <= nextUpdate.getTime() + tolerableValidity;
    }