private List<String> getListDiff(final List<String> preList, final List<String> lastList) {
        if (CollectionUtils.isEmpty(lastList)) {
            return Collections.emptyList();
        }
        
        if (CollectionUtils.isEmpty(preList)) {
            return lastList;
        }
        
        Map<String, Integer> map = preList.stream()
                .distinct()
                .collect(Collectors.toMap(Function.identity(), source -> 1));
        return lastList.stream()
                .filter(item -> !map.containsKey(item))
                .collect(Collectors.toList());
    }
get two list different.

@param preList {@linkplain List}
@param lastList {@linkplain List}
@return {@linkplain List}
shenyu-admin/src/main/java/org/apache/shenyu/admin/service/impl/PermissionServiceImpl.java