docs: @Nonnull
    public static EChange setUseSTARTTLS (final boolean bUseSTARTTLS)
    {
      return s_aRWLock.writeLocked ( () -> {
        if (s_bUseSTARTTLS == bUseSTARTTLS)
          return EChange.UNCHANGED;
        s_bUseSTARTTLS = bUseSTARTTLS;
        return EChange.CHANGED;
      });
    }