docs: @SuppressWarnings("InsecureCryptoUsage") // Only used in known-weak crypto "legacy" mode.
    static byte[] aes128Encrypt(StringBuilder message, String key) {
      try {
        key = normalizeString(key, 16);
        rightPadString(message, '{', 16);
        Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key.getBytes(), "AES"));
        return cipher.doFinal(message.toString().getBytes());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }