docs: public static <T> Map<T, Integer> countMap(Iterator<T> iter) {
  		final HashMap<T, Integer> countMap = new HashMap<>();
  		if (null != iter) {
  			Integer count;
  			T t;
  			while (iter.hasNext()) {
  				t = iter.next();
  				count = countMap.get(t);
  				if (null == count) {
  					countMap.put(t, 1);
  				} else {
  					countMap.put(t, count + 1);
  				}
  			}
  		}
  		return countMap;
  	}