docs: public static KeyGroupRange computeKeyGroupRangeForOperatorIndex(
  		int maxParallelism,
  		int parallelism,
  		int operatorIndex) {
  
  		checkParallelismPreconditions(parallelism);
  		checkParallelismPreconditions(maxParallelism);
  
  		Preconditions.checkArgument(maxParallelism >= parallelism,
  			"Maximum parallelism must not be smaller than parallelism.");
  
  		int start = ((operatorIndex * maxParallelism + parallelism - 1) / parallelism);
  		int end = ((operatorIndex + 1) * maxParallelism - 1) / parallelism;
  		return new KeyGroupRange(start, end);
  	}