How to use the @aws-cdk/aws-iam.ManagedPolicy.fromAwsManagedPolicyName function in @aws-cdk/aws-iam

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', {
      assumedBy: new ServicePrincipal('codedeploy.amazonaws.com'),
      managedPolicies: [ ManagedPolicy.fromAwsManagedPolicyName('AWSCodeDeployRoleForECS') ]
    });
  }
}

}

    const instanceCount = props.instances != null ? props.instances : 2;
    if (instanceCount < 1) {
      throw new Error('At least one instance is required');
    }

    // Get the actual subnet objects so we can depend on internet connectivity.
    const internetConnected = props.instanceProps.vpc.selectSubnets(props.instanceProps.vpcSubnets).internetConnectivityEstablished;

    let monitoringRole;
    if (props.monitoringInterval && props.monitoringInterval.toSeconds()) {
      monitoringRole = props.monitoringRole || new Role(this, "MonitoringRole", {
        assumedBy: new ServicePrincipal("monitoring.rds.amazonaws.com"),
        managedPolicies: [
          ManagedPolicy.fromAwsManagedPolicyName('service-role/AmazonRDSEnhancedMonitoringRole')
        ]
      });
    }

    for (let i = 0; i < instanceCount; i++) {
      const instanceIndex = i + 1;

      const instanceIdentifier = props.instanceIdentifierBase != null ? `${props.instanceIdentifierBase}${instanceIndex}` :
                     props.clusterIdentifier != null ? `${props.clusterIdentifier}instance${instanceIndex}` :
                     undefined;

      const publiclyAccessible = props.instanceProps.vpcSubnets && props.instanceProps.vpcSubnets.subnetType === ec2.SubnetType.PUBLIC;

      const instance = new CfnDBInstance(this, `Instance${instanceIndex}`, {
        // Link to cluster
        engine: props.engine.name,

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', {
      assumedBy: new ServicePrincipal('codedeploy.amazonaws.com'),
      managedPolicies: [ ManagedPolicy.fromAwsManagedPolicyName('AWSCodeDeployRoleForECS') ]
    });
  }
}

type: AttributeType.STRING
      },
      billingMode: BillingMode.PAY_PER_REQUEST,
      stream: StreamViewType.NEW_IMAGE,

      // The default removal policy is RETAIN, which means that cdk destroy will not attempt to delete
      // the new table, and it will remain in your account until manually deleted. By setting the policy to 
      // DESTROY, cdk destroy will delete the table (even if it has data in it)
      removalPolicy: cdk.RemovalPolicy.DESTROY, // NOT recommended for production code
    });

    const itemsTableRole = new Role(this, 'ItemsDynamoDBRole', {
      assumedBy: new ServicePrincipal('appsync.amazonaws.com')
    });

    itemsTableRole.addManagedPolicy(ManagedPolicy.fromAwsManagedPolicyName('AmazonDynamoDBFullAccess'));

    const dataSource = new CfnDataSource(this, 'ItemsDataSource', {
      apiId: itemsGraphQLApi.attrApiId,
      name: 'ItemsDynamoDataSource',
      type: 'AMAZON_DYNAMODB',
      dynamoDbConfig: {
        tableName: itemsTable.tableName,
        awsRegion: this.region
      },
      serviceRoleArn: itemsTableRole.roleArn
    });

    const getOneResolver = new CfnResolver(this, 'GetOneQueryResolver', {
      apiId: itemsGraphQLApi.attrApiId,
      typeName: 'Query',
      fieldName: 'getOne',