关于lambda:lambda-生成笛卡尔集

public static void getDiKaEr() {    List<List<String>> source = new ArrayList<>(); List<String> color = Arrays.asList("红色", "红色", "蓝色"); List<String> size = Arrays.asList("中", "大", "小"); List<String> origins = Arrays.asList("中国", "瑞士"); source.add(color); source.add(size); source.add(origins); List<String> result = source.stream().reduce((a, b) -> {        List<String> results = new ArrayList<>(); a.forEach(param1 -> {            b.forEach(param2 -> {                results.add(param1 + "-" + param2); }); }); return results; }).get(); System.out.println(result);}