docs: public String getCrc32cToHexString() {
      if (crc32c == null) {
        return null;
      }
      byte[] decodeCrc32c = BaseEncoding.base64().decode(crc32c);
      StringBuilder stringBuilder = new StringBuilder();
      for (byte b : decodeCrc32c) {
        stringBuilder.append(String.format("%02x", b & 0xff));
      }
      return stringBuilder.toString();
    }