public class MapStateMachine extends StateMachine {
  private Map<Object, Object> map = new HashMap<>();

  public Object putWithTtl(Commit<PutWithTtl> commit) {
    map.put(commit.operation().key, commit);
    executor.schedule(Duration.ofMillis(commit.operation().ttl, () -> {
      map.remove(commit.operation().key);
      commit.release();
    });
  }
}