续费余额缴费金额出错

mec-biz/src/main/java/com/ym/mec/biz/service/impl/ClassGroupServiceImpl.java

@@ -635,7 +635,7 @@ public class ClassGroupServiceImpl extends BaseServiceImpl<Integer, ClassGroup>
             musicGroupDao.update(musicGroup);
         }
         if(classGroupAndTeachers == null || classGroupAndTeachers.size()==0){
-            return classGroupAndTeachers;
+            return null;
         }
 
         List<Integer> classGroupIds = classGroupAndTeachers.stream().map(ClassGroupTeachersDto::getId).collect(Collectors.toList());