How to use the @aws-cdk/aws-events-targets.EcsTask function in @aws-cdk/aws-events-targets

// Run at 2am EST (6am UTC) every night
      schedule: events.Schedule.expression("cron(0 6 * * ? *)"),
      description: "Starts the CloudMapper auditing task every night",
      targets: [new targets.EcsTask({
        cluster: cluster,
        taskDefinition: taskDefinition,
        subnetSelection: {subnetType: ec2.SubnetType.PUBLIC}
      })]
    });

    // Create rule to trigger this manually
    new events.Rule(this, "manual_run", {
      ruleName: "cloudmapper_manual_run",
      eventPattern: {source: ['cloudmapper']},
      description: "Allows CloudMapper auditing to be manually started",
      targets: [new targets.EcsTask({
        cluster: cluster,
        taskDefinition: taskDefinition,
        subnetSelection: {subnetType: ec2.SubnetType.PUBLIC}
      })]
    });

    // Create alarm for any errors
    const error_alarm =  new cloudwatch.Alarm(this, "error_alarm", {
      metric: new cloudwatch.Metric({
        namespace: 'cloudmapper',
        metricName: "errors",
        statistic: "Sum"
      }),
      threshold: 0,
      evaluationPeriods: 1,
      datapointsToAlarm: 1,

protected addTaskDefinitionToEventTarget(taskDefinition: TaskDefinition): EcsTask {
    // Use the EcsTask as the target of the EventRule
    const eventRuleTarget = new EcsTask( {
      cluster: this.cluster,
      taskDefinition,
      taskCount: this.desiredTaskCount
    });

    this.eventRule.addTarget(eventRuleTarget);

    return eventRuleTarget;
  }