title: AWS CloudFormation Is failing with error "Encountered unsupported property name"
body: <p>I am trying to create an alarm based on anomaly detection model with below CloudFormation template and getting an error :</p>
  
  <p>Can someone help me with this.</p>
  
  <pre><code>"Resources": {
      "CPUUtilizationAlarm": {
         "Type": "AWS::CloudWatch::Alarm",
         "Properties": {
            "AlarmDescription": "Alarm Triggered",
            "AlarmName": "CPUUtilizationAlarm",
            "ComparisonOperator": "GreaterThanUpperThreshold",
            "EvaluationPeriods": 1,
            "Dimensions": [],
            "Metrics": [
               {
                  "Expression": "ANOMALY_DETECTION_BAND(m1, 10)",
                  "Id": "ad1"
               },
               {
                  "Id": "m1",
                  "MetricStat": {
                     "Metric": {
                        "MetricName": "CPUUtilization",
                        "Namespace": "AWS/EC2",
                        "Dimensions": [
                          {
                            "value": "i-05157fe1be36d52bd",
                            "name": "InstanceId"
                          }
                        ],
                      },
                     "Period": 60,
                     "Stat": "Average"
                  }
               }
            ],
            "ThresholdMetricId": "ad1",
            "TreatMissingData": "breaching",
         }
      }
   }
  </code></pre>