如何在CDK中创建NAT网关，然后添加指向其CIDR的内网路由？

import * as cdk from 'aws-cdk-lib';
import * as ec2 from 'aws-cdk-lib/aws-ec2';

const app = new cdk.App();
const stack = new cdk.Stack(app, 'MyStack');

const vpc = new ec2.Vpc(stack, 'MyVpc', {
  cidr: '10.0.0.0/16',
  maxAzs: 2,
  subnetConfiguration: [
    {
      cidrMask: 24,
      name: 'Public',
      subnetType: ec2.SubnetType.PUBLIC,
    },
    {
      cidrMask: 24,
      name: 'Private',
      subnetType: ec2.SubnetType.PRIVATE,
    },
  ],
});

const natGateway = new ec2.NatGateway(stack, 'MyNatGateway', {
  vpc,
  subnetSelection: { subnetType: ec2.SubnetType.PUBLIC },
});

const privateRouteTable = new ec2.PrivateSubnet(stack, 'MyPrivateSubnet', {
  vpc,
}).routeTable;

privateRouteTable.addRoute('DefaultRoute', {
  routerType: ec2.RouterType.NAT_GATEWAY,
  routerId: natGateway.natGatewayId,
});

cdk.Deploy(stack);