Nov12

Creating pull request for code review. See comments in diff.
We don't need this class. You did something similar in UnloadBuffer. Why do we such a complicated factory for something that literally occurs once? 

in Main, you could just fill the Holders in the racetrack or the racetrackline like:
IntStream.range(0, 70).forEach(e -> racetrackLine.queue(new SampleHolder());