Not able to retrive all groups using REST api. admin/directory/v1/groups returns 400 code

[ibmappcon]

There is a issue with REST api when try to retrieve all groups using Below url We are getting 400 error https://admin.googleapis.com/admin/directory/v1/groups

{ "error": { "code": 400, "message": "Bad Request", "errors": [ { "message": "Bad Request", "domain": "global", "reason": "badRequest" } ] } }