argo events cannot be Unmarshaled

[caibirdme]

Here's argo events' data

    {
        "context": {
          "type": "type_of_event_source",
          "specversion": "cloud_events_version",
          "source": "name_of_the_event_source",
          "id": "unique_event_id",
          "time": "event_time",
          "datacontenttype": "type_of_data",
          "subject": "name_of_the_configuration_within_event_source"
        },
        "data": {
          "header": {},
          "body": {},
        }
    }

But when I run

ev := cloudevents.NewEvent()
err := json.Unmarshal(data, &ev)

it reports error. It seems that attributes shouldn't be wrapped into context key?

And here's argo events' doc: https://argoproj.github.io/argo-events/tutorials/02-parameterization/#webhook-event-payload