code: public Set<String> generateIdsToUse(long nextFreeTransactionalId) {
  		Set<String> transactionalIds = new HashSet<>();
  		for (int i = 0; i < poolSize; i++) {
  			long transactionalId = nextFreeTransactionalId + subtaskIndex * poolSize + i;
  			transactionalIds.add(generateTransactionalId(transactionalId));
  		}
  		return transactionalIds;
  	}
docs: Range of available transactional ids to use is:
  [nextFreeTransactionalId, nextFreeTransactionalId + parallelism * kafkaProducersPoolSize)
  loop below picks in a deterministic way a subrange of those available transactional ids based on index of
  this subtask.