java8 list转map把key重复的value合并

无序

Map<String, List<GeneralVO>> groupMap = generalVOS.stream().collect(Collectors.groupingBy(GeneralVO::getTaskId));

有序

 Map<String, List<GeneralVO>> groupMap2 = generalVOS.stream().collect(Collectors.groupingBy(GeneralVO::getTaskId,LinkedHashMap::new,Collectors.toList()));