docs: @Nonnull
    public static EChange setExpirationSeconds (final int nExpirationSeconds)
    {
      return s_aRWLock.writeLocked ( () -> {
        if (s_nExpirationSeconds == nExpirationSeconds)
          return EChange.UNCHANGED;
        s_nExpirationSeconds = nExpirationSeconds;
        LOGGER.info ("ResponseHelper expirationSeconds=" + nExpirationSeconds);
        return EChange.CHANGED;
      });
    }