docs: public String getMd5ToHexString() {
      if (md5 == null) {
        return null;
      }
      byte[] decodedMd5 = BaseEncoding.base64().decode(md5);
      StringBuilder stringBuilder = new StringBuilder();
      for (byte b : decodedMd5) {
        stringBuilder.append(String.format("%02x", b & 0xff));
      }
      return stringBuilder.toString();
    }