docs: public static <T> Set<T> randomEleSet(Collection<T> collection, int count) {
  		ArrayList<T> source = new ArrayList<>(new HashSet<>(collection));
  		if (count > source.size()) {
  			throw new IllegalArgumentException("Count is larger than collection distinct size !");
  		}
  
  		final HashSet<T> result = new HashSet<T>(count);
  		int limit = collection.size();
  		while (result.size() < count) {
  			result.add(randomEle(source, limit));
  		}
  
  		return result;
  	}