优化

sckw-modules/sckw-system/src/main/java/com/sckw/system/dubbo/RemoteSystemServiceImpl.java

@@ -490,7 +490,7 @@ public class RemoteSystemServiceImpl implements RemoteSystemService {
     @Override
     public Map<Long, UserCacheResDto> queryUserCacheMapByIds(List<Long> userIds) {
         if (CollectionUtils.isEmpty(userIds)) {
-            return null;
+            return Collections.emptyMap();
         }
         List<UserCacheResDto> userCacheResDtos = queryUserCacheByIds(userIds);
         if (CollectionUtils.isEmpty(userCacheResDtos)) {