code: public static <K, I, O, A> StreamReducerSimple<K, I, O, A> create(Function<I, K> keyFunction,
  			Comparator<K> keyComparator,
  			Reducer<K, I, O, A> reducer) {
  		return new StreamReducerSimple<>(keyFunction, keyComparator, reducer);
  	}
docs: Creates a new instance of  StreamReducerSimple
  
  @param keyComparator comparator for compare keys
  @param keyFunction   function for counting key