List list = Lists.newArrayList();
list.add(OptionDTO.builder().value(1).name("张三").build());
list.add(OptionDTO.builder().value(2).name("李四").build());
list.add(OptionDTO.builder().value(3).name("王五").build());
List> listList = Lists.newArrayList();
listList.add(list);
List flatList=listList.stream().flatMap(Collection::stream).collect(Collectors.toList());
System.out.println(JSON.toJSONString(flatList));
=========================
[{"name":"张三","value":1},{"name":"李四","value":2},{"name":"王五","value":3}]
