code: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new IllegalArgumentException();
      }
  
      switch (field) {
      case ACKNOWLEDGED_BY:
        return isSetAcknowledged_by();
      case ACKNOWLEDGED_BY_BATCHLOG:
        return isSetAcknowledged_by_batchlog();
      case PAXOS_IN_PROGRESS:
        return isSetPaxos_in_progress();
      }
      throw new IllegalStateException();
    }
docs: Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise