Rest Post operation is not working for group

Rest Post operation is not working for group function.

when adding new group, Post operation is not working, getting "400" error code.

But Put is working for adding groups to the controller.

i have used to add following group action

{"group": [{"group-name": "TestFlow-0", "buckets": {"bucket": [{"action": [{"order": 0, "pop-vlan-action": {}}], "bucket-id": 0, "watch_group": 0}]}, "group-type": "group-indirect", "group-id": 9, "barrier": "false"}]}