How to use the @aws-cdk/aws-elasticloadbalancingv2.HttpCodeTarget.TARGET_5XX_COUNT function in @aws-cdk/aws-elasticloadbalancingv2

new Alarm(this, 'TargetGroup5xx', {
      metric: tg1.metricHttpCodeTarget(HttpCodeTarget.TARGET_5XX_COUNT),
      threshold: 1,
      evaluationPeriods: 1,
      period: cdk.Duration.minutes(1)
    });

    new Alarm(this, 'TargetGroup2UnhealthyHosts', {
      metric: tg2.metricUnhealthyHostCount(),
      threshold: 1,
      evaluationPeriods: 2,
    });

    new Alarm(this, 'TargetGroup25xx', {
      metric: tg2.metricHttpCodeTarget(HttpCodeTarget.TARGET_5XX_COUNT),
      threshold: 1,
      evaluationPeriods: 1,
      period: cdk.Duration.minutes(1)
    });

    // Roles
    new Role(this, 'ServiceTaskDefExecutionRole', {
      assumedBy: new ServicePrincipal('ecs-tasks.amazonaws.com'),
      managedPolicies: [ ManagedPolicy.fromAwsManagedPolicyName('service-role/AmazonECSTaskExecutionRolePolicy') ]
    });

    new Role(this, 'ServiceTaskDefTaskRole', {
      assumedBy: new ServicePrincipal('ecs-tasks.amazonaws.com'),
    });

    new Role(this, 'CodeDeployRole', {

healthyHttpCodes: '200',
        healthyThresholdCount: 2,
        unhealthyThresholdCount: 3,
        timeout: cdk.Duration.seconds(4)
      }
    });

    // Alarms: monitor 500s and unhealthy hosts on target groups
    new Alarm(this, 'TargetGroupUnhealthyHosts', {
      metric: tg1.metricUnhealthyHostCount(),
      threshold: 1,
      evaluationPeriods: 2,
    });

    new Alarm(this, 'TargetGroup5xx', {
      metric: tg1.metricHttpCodeTarget(HttpCodeTarget.TARGET_5XX_COUNT),
      threshold: 1,
      evaluationPeriods: 1,
      period: cdk.Duration.minutes(1)
    });

    new Alarm(this, 'TargetGroup2UnhealthyHosts', {
      metric: tg2.metricUnhealthyHostCount(),
      threshold: 1,
      evaluationPeriods: 2,
    });

    new Alarm(this, 'TargetGroup25xx', {
      metric: tg2.metricHttpCodeTarget(HttpCodeTarget.TARGET_5XX_COUNT),
      threshold: 1,
      evaluationPeriods: 1,
      period: cdk.Duration.minutes(1)