Feature Gap / Interface Mismatch: AlarmWidget, Alarm, and IAlarm

[BBonifield]

I'm not sure if this is intended or an oversight, but AlarmWidgetProps is setup with readonly alarm: Alarm; rather than readonly alarm: IAlarm;. This prevents you from referencing alarms via Cloudwatch.Alarm.fromAlarmArn, which returns an IAlarm.

I ask because, for the underlying Cloudformation DashboadBody, I believe the following JSON structure is allowed, and it only requires the ARN:

{
  "type": "metric",
  "x": 0,
  "y": 6,
  "width": 6,
  "height": 3,
  "properties": {
    "title": "Availability (%)",
    "annotations": {
      "alarms": [
        "arn:aws:cloudwatch:some-specific-arn"
      ]
    },
    "view": "timeSeries",
    "stacked": false
  }
},

Thanks!

[eladb]

Confirming this is an issue. @shivlaks we should update our awslint rule to cover more than just props...