@Override
public void process(IncomingMessageEnvelope envelope,
                    MessageCollector collector,
                    TaskCoordinator coordinator) throws Exception {
  String key = (String)envelope.getKey();
  String message = (String)envelope.getMessage();

  try {
    LocalDateTime localDateTime = LocalDateTime.parse(key, formatter);
    Quotes quotes = unmarshal(message);
    stateStore.put(localDateTime, quotes);
  } catch (Exception e) {
    ...
  }
}