docs: private void tick(long index, long timestamp) {
      this.currentIndex = index;
  
      // If the entry timestamp is less than the current state machine timestamp
      // and the delta is not yet set, set the delta and do not change the current timestamp.
      // If the entry timestamp is less than the current state machine timestamp
      // and the delta is set, update the current timestamp to the entry timestamp plus the delta.
      // If the entry timestamp is greater than or equal to the current timestamp, update the current
      // timestamp and reset the delta.
      if (timestamp < currentTimestamp) {
        if (timestampDelta == 0) {
          timestampDelta = currentTimestamp - timestamp;
        } else {
          currentTimestamp = timestamp + timestampDelta;
        }
      } else {
        currentTimestamp = timestamp;
        timestampDelta = 0;
      }
  
      // Set the current operation type to COMMAND to allow events to be sent.
      setOperation(OperationType.COMMAND);
  
      service.tick(WallClockTimestamp.from(timestamp));
    }