Google Classroom Add IAM Policy Binding

I am working on Google Classroom Pub/Sub Notification. I have task which is create the pub/sub topic and subscription by using the Rest API. I have created the pub/sub topic successfully but when i am setting the IAM Policy/Permissions for created topic then i am getting the error message.

API URL:- https://pubsub.googleapis.com/v1/projects/project-abc/topics/xyz-topic-101:setIamPolicy API Method:- POST API Request Body:-

{
    "policy": {
        "bindings": [
            {
                "role": "roles/owner",
                "members": [
                    "abc@domain.com",
                    "classroom-notifications@system.gserviceaccount.com"
                ]
            },
            {
                "role": "roles/pubsub.admin",
                "members": [
                    "abc@domain.com",
                    "classroom-notifications@system.gserviceaccount.com"
                ]
            },
            {
                "role": "roles/pubsub.editor",
                "members": [
                    "abc@domain.com",
                    "classroom-notifications@system.gserviceaccount.com"
                ]
            },
            {
                "role": "roles/pubsub.publisher",
                "members": [
                    "abc@domain.com",
                    "classroom-notifications@system.gserviceaccount.com"
                ]
            },
            {
                "role": "roles/pubsub.subscriber",
                "members": [
                    "abc@domain.com",
                    "classroom-notifications@system.gserviceaccount.com"
                ]
            }
        ],
        "version": 1
    }
}

API Response:- { "error": { "code": 400, "message": "The member abc@domain.com is of an unknown type. Please set a valid type prefix for the member.", "status": "INVALID_ARGUMENT" } }

I have follow the below Google Doc Link:- https://cloud.google.com/pubsub/docs/reference/rest/v1/Policy#Binding I am not getting that why this message is coming. Please share your suggestions & feedback's.