code: private static String calculateChecksum(String string) {
          byte[] bytes = string.getBytes(UTF_8);
          Checksum checksum = new CRC32();
          checksum.update(bytes, 0, bytes.length);
          return Long.toHexString(checksum.getValue()).toUpperCase();
      }
docs: Calculates a checksum for a given string.
  
  @param string string from which a checksum should be obtained
  @return a checksum allowing two events with the same properties to be grouped later.