CDK generates alarm with both ExtendedStatistic and Statistic when percentile is used

[yukuan1988]

description of the bug: when I use percentile in Statistic, alarm is generated with both Statistic and ExtendedStatistic.

Reproduction Steps

CDK code:

function getAlarm(construct: cdk.Construct, id: string, alarmName: string, metricName: string, threshold: number, alarmDescription: string, statistic: string): Alarm {
            return new Alarm(construct, id, {
                alarmName,
                alarmDescription,
                metric: new Metric({
                    namespace: 'AWS/ES',
                    metricName,
                    dimensions: {
                        DomainName: esDomain.domainName,
                        ClientId: account
                    }
                }),
                threshold,
                statistic,
                evaluationPeriods: 3,
                period: cdk.Duration.minutes(5),
                comparisonOperator: ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD,
                treatMissingData: TreatMissingData.NOT_BREACHING
            });
        }

            getAlarm(this, 'ES_DOMAIN_HIGHWRITELATENCY_ALARM', 'ES_DOMAIN_HIGHWRITELATENCY', 'WriteLatency', 2/* seconds */, 'Alarm for when the ES cluster has high write latency', 'p90'),

Generated template:

"ESDOMAINHIGHWRITELATENCYALARM8819DAF6": {
        "Type": "AWS::CloudWatch::Alarm",
        "Properties": {
          "ComparisonOperator": "GreaterThanOrEqualToThreshold",
          "EvaluationPeriods": 3,
          "AlarmDescription": "Alarm for when the ES cluster has high write latency",
          "AlarmName": "ES_DOMAIN_HIGHWRITELATENCY",
          "Dimensions": [
            {
              "Name": "ClientId",
              "Value": "453055088523"
            },
            {
              "Name": "DomainName",
              "Value": "contents-simonyu"
            }
          ],
          "ExtendedStatistic": "p90",
          "MetricName": "WriteLatency",
          "Namespace": "AWS/ES",
          "Period": 300,
          "Statistic": "Average",
          "Threshold": 2,
          "TreatMissingData": "notBreaching"
        },
        "Metadata": {
          "aws:cdk:path": "Monitoring-Dev-simonyu/ES_DOMAIN_HIGHWRITELATENCY_ALARM/Resource"
        }
      },

Error Log

Environment

• **CLI Version : 1.23.0
• **Framework Version: 1.23.0
• **OS : MacOS & Linux
• **Language : TypeScript

Other

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