added new endpoint

src/controllers/group.js

@@ -49,6 +49,14 @@ class GroupController {
         return res.status(200).send(group["id"].toString());
     }
 
+    async getById(req, res) {
+        let groupId = req.params.groupId;
+
+        let groupName = (await GroupService.getById(groupId)).name;
+
+        return res.status(200).send(groupName);
+    }
+
     async getUsersInGroup(req, res) {
 
         const groupId = req.params.groupId;