How to use the @aws-cdk/aws-appsync.CfnDataSource function in @aws-cdk/aws-appsync

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',
      dataSourceName: dataSource.name,
      requestMappingTemplate: `{