How to use the cloudform-types.Fn.Ref function in cloudform-types

(acc, k) => ({
        ...acc,
        [k]: customStackParams[k],
      }),
      {}
    );

    transformStacks[userStack] = userDefinedStack;
    // Split on non alphabetic characters to make a valid resource id.
    const stackResourceId = userStack.split(/[^A-Za-z]/).join('');
    const customNestedStack = new CloudFormation.Stack({
      Parameters: parametersForStack,
      TemplateURL: Fn.Join('/', [
        'https://s3.amazonaws.com',
        Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        'stacks',
        userStack,
      ]),
    }).dependsOn(allResourceIds);
    rootStack.Resources[stackResourceId] = customNestedStack;
  }

  // Update the Root Stack Params since we have added the Child Stack Params if they are missing.
  rootStack.Parameters = updatedParameters;
  return {
    ...transformOutput,
    resolvers: transformResolvers,
    stacks: transformStacks,
  };
}

role = (name: string, region: string): any => {
    return new IAM.Role({
      RoleName: Fn.If(
        ResourceConstants.CONDITIONS.HasEnvironmentParameter,
        Fn.Join('-', [
          FunctionResourceIDs.FunctionIAMRoleName(name, true), // max of 64. 64-10-26-28 = 0
          Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'), // 26
          Fn.Ref(ResourceConstants.PARAMETERS.Env), // 10
        ]),
        Fn.Join('-', [
          FunctionResourceIDs.FunctionIAMRoleName(name, false), // max of 64. 64-26-38 = 0
          Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'), // 26
        ])
      ),
      AssumeRolePolicyDocument: {
        Version: '2012-10-17',
        Statement: [
          {
            Effect: 'Allow',
            Principal: {
              Service: 'appsync.amazonaws.com',
            },
            Action: 'sts:AssumeRole',
          },

export function syncLambdaIAMRole({ name, region }: { name: string; region?: string }) {
    return new IAM.Role({
      RoleName: Fn.If(
        ResourceConstants.CONDITIONS.HasEnvironmentParameter,
        Fn.Join('-', [
          name.slice(0, 26), // max of 64. 64-10-26-28 = 0
          Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'), // 26
          Fn.Ref(ResourceConstants.PARAMETERS.Env), // 10
        ]),
        Fn.Join('-', [
          // tslint:disable-next-line: no-magic-numbers
          name.slice(0, 37), // max of 64. 64-26-38 = 0
          Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'), // 26
        ])
      ),
      AssumeRolePolicyDocument: {
        Version: '2012-10-17',
        Statement: [
          {
            Effect: 'Allow',
            Principal: {
              Service: 'appsync.amazonaws.com',
            },
            Action: 'sts:AssumeRole',

public makeDynamoDBStreamingFunction() {
    return new Lambda.Function({
      Code: {
        S3Bucket: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        S3Key: Fn.Join('/', [
          Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
          'functions',
          Fn.Join('.', [ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaFunctionLogicalID, 'zip']),
        ]),
      },
      FunctionName: this.joinWithEnv('-', [
        Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingFunctionName),
        Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'),
      ]),
      Handler: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingLambdaHandlerName),
      Role: Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaIAMRoleLogicalID, 'Arn'),
      Runtime: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingLambdaRuntime),
      Layers: [Fn.FindInMap('LayerResourceMapping', Fn.Ref('AWS::Region'), 'layerRegion')],
      Environment: {
        Variables: {
          ES_ENDPOINT: Fn.Join('', ['https://', Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID, 'DomainEndpoint')]),
          ES_REGION: Fn.Select(3, Fn.Split(':', Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID, 'DomainArn'))),
          DEBUG: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchDebugStreamingLambda),
        },
      },
    }).dependsOn([
      ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaIAMRoleLogicalID,
      ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID,
    ]);
  }

S3Key: Fn.Join('/', [
                    Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
                    "functions",
                    Fn.Join('.', [
                        ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaFunctionLogicalID,
                        "zip"
                    ]),
                ])
            },
            FunctionName: this.joinWithEnv("-", [
                Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingFunctionName),
                Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'),
            ]),
            Handler: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingLambdaHandlerName),
            Role: Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaIAMRoleLogicalID, 'Arn'),
            Runtime: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchStreamingLambdaRuntime),
            Environment: {
                Variables: {
                    ES_ENDPOINT: Fn.Join('', [
                        'https://',
                        Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID, 'DomainEndpoint')
                    ]),
                    ES_REGION: Fn.Select(3, Fn.Split(':', Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID, 'DomainArn'))),
                    DEBUG: Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchDebugStreamingLambda)
                }
            }
        }).dependsOn([
            ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaIAMRoleLogicalID,
            ResourceConstants.RESOURCES.ElasticsearchDomainLogicalID
        ])
    }

}),
      ])
    );

    const resTemplate = print(ref('utils.toJson($utils.parseJson($utils.rds.toJsonString($ctx.result))[1][0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      TypeName: mutationTypeName,
      FieldName: fieldName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);
    return resolver;
  }

public makeDynamoDBStreamEventSourceMapping(typeName: string) {
        return new Lambda.EventSourceMapping({
            BatchSize: 1,
            Enabled: true,
            EventSourceArn: Fn.ImportValue(
                Fn.Join(
                    ':',
                    [Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId), "GetAtt", ModelResourceIDs.ModelTableResourceID(typeName), "StreamArn"]
                )
            ),
            FunctionName: Fn.GetAtt(ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaFunctionLogicalID, 'Arn'),
            StartingPosition: 'LATEST'
        }).dependsOn([
            ResourceConstants.RESOURCES.ElasticsearchStreamingLambdaFunctionLogicalID
        ])
    }

public makeElasticsearchAccessIAMRole() {
    return new IAM.Role({
      RoleName: this.joinWithEnv('-', [
        Fn.Ref(ResourceConstants.PARAMETERS.ElasticsearchAccessIAMRoleName),
        Fn.GetAtt(ResourceConstants.RESOURCES.GraphQLAPILogicalID, 'ApiId'),
      ]),
      AssumeRolePolicyDocument: {
        Version: '2012-10-17',
        Statement: [
          {
            Effect: 'Allow',
            Principal: {
              Service: 'appsync.amazonaws.com',
            },
            Action: 'sts:AssumeRole',
          },
        ],
      },
      Policies: [
        new IAM.Role.Policy({