解决班级创建时如果没有学员，没有创建群聊的bug

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

@@ -287,6 +287,16 @@ public class ClassGroupServiceImpl extends BaseServiceImpl<Integer, ClassGroup>
         // 加入IM群组
         if (userIdList.size() > 0) {
             addImGroup(classGroup, userIdList, teacherIdList);
+        }else {
+            Map<Integer,String> userRoleMap = new HashMap<>();
+            if(teacherIdList != null && teacherIdList.size() > 0){
+                for(Integer teacherId : teacherIdList){
+                    userRoleMap.put(teacherId, "指导老师");
+                }
+            }
+            MusicGroup musicGroup = musicGroupDao.get(classGroup.getMusicGroupId());
+            imGroupService.create(classGroup.getId().longValue(), null, classGroup.getName(), musicGroup.getName(), musicGroup.getName(), musicGroup.getName(), null, "MUSIC");
+            imGroupMemberService.join(classGroup.getId().longValue(), userRoleMap);
         }
         return true;
     }