OpenApiGatewayToLambda: "CustomResource attribute error: Vendor response doesn't contain TemplateOutputKey attribute"

I'm currently trying to deploy my OpenApiGatewayToLambda, but getting the error mentioned in the title. The error indicates that the OpenApiGatewayToLambdaApiTemplateWriterCustomResource object is causing the issue. It used to work some days ago, but i already reupdated all package versions to the versions that used to work. Without success. After some investigation i found out that the TemplateOutputKey is generated in the [template-writer-custom-resource](https://github.com/awslabs/aws-solutions-constructs/tree/39843c151078e547810c4fec15ff54d351da56f3/source/patterns/%40aws-solutions-constructs/resources/lib/template-writer-custom-resource) from aws-solutions-constructs:

` const templateOutputKey = crypto.randomBytes(32).toString('hex');
`

and then used in the responseData:

`responseData = {
TemplateOutputKey: templateOutputKey
};
`

This lambda tries to send data to the cdk asset bucket that gets generated while bootstrapping. When going into the lambdas logs i found this error:

"User: arn:aws:sts::xxx:assumed-role/api-gateway-stack-OpenApiGatewayToLambda/api-gateway-stack-OpenApiGatewayToLambda is not authorized to perform: s3:PutObject on resource: \"arn:aws:s3:::cdk-assets-xxx-eu-west-1\" with an explicit deny in a resource-based policy"

When looking into the Bucket Policy, i see that it only allows PutObject if kms headers are passed.

Looking back to the template-writer-custom-resource (Lambda) it sends the data to S3 without encryption:

`await s3Client.send(new PutObjectCommand({
Bucket: templateOutputBucket,
Key: templateOutputKey,
Body: template
// ❌ Missing: ServerSideEncryption: 'aws:kms'
}));`

Has anybody an idea what i'm missing out of a sudden? Do i have to adapt the policies?

### Reproduction Steps
Here is all my Constructs Code. I already checked if some properties are not passed properly, but this isn't the case. It just does not deploy. I also checked my OpenAPI Spec. It is also not the problem.

// For private endpoints, use proper IVpcEndpoint[] array
if (isPrivate && vpcEndpointService) {
endpointConfiguration = {
types: [EndpointType.PRIVATE],
vpcEndpoints: [vpcEndpointService],
};
}

// Create the API Gateway
const apiGatewayConstruct = new OpenApiGatewayToLambda(this, 'OpenApiGatewayToLambda', {
apiDefinitionAsset,
apiGatewayProps: {
deployOptions: {
stageName: props.stageName,
loggingLevel: MethodLoggingLevel.INFO,
metricsEnabled: true,
tracingEnabled: true,
accessLogDestination: accessLogDestination,
accessLogFormat: AccessLogFormat.clf(),
variables: {
...(authorizerLambda && { authorizerName: authorizerLambda.functionName }),
dispatcherLambdaName: props.dispatcherLambdaName,
getLambdaName: props.getLambdaName,
region: Stack.of(this).region,
accountId: Stack.of(this).account,
},
},
restApiName: `${props.apiName}-${isPrivate ? 'private' : 'public'}`,
description: `API Gateway for managing AWS Workspaces (${props.apiVersion}) - ${isPrivate ? 'Private' : 'Public'}`,
endpointConfiguration: endpointConfiguration,
// Resource policy for private API Gateway
...(isPrivate && {
policy: this.createPrivateApiResourcePolicy(props.vpcEndpointId),
}),
},
apiIntegrations: [
{
id: 'DispatcherLambda',
existingLambdaObj: LambdaFunction.fromFunctionName(
this,
'DispatcherLambda',
props.dispatcherLambdaName,
) as LambdaFunction,
},
{
id: 'GetLambda',
existingLambdaObj: LambdaFunction.fromFunctionName(
this,
'GetLambda',
props.getLambdaName,
) as LambdaFunction,
},
],
});`

### Error Log

CustomResource attribute error: Vendor response doesn't contain TemplateOutputKey attribute in object arn:aws:cloudformation:eu-west-1:xxx:stack/vClient-api-gateway-stack-dev/f15614b0-52a4-11
f0-ae21-02f95d261deb|OpenApiGatewayToLambdaApiTemplateWriterCustomResource957D1BA4|c7cf2bdd-f83c-40ba-be5a-0925fafeb017

### Environment

- **CDK CLI Version :** 2.1006.0
- **CDK Framework Version:** 2.193.0
- **AWS Solutions Constructs Version:** 2.85.2
- **OS : MACOS
- **Language :** Typescript, English

---

This is :bug: Bug Report

Start in source/patterns/@aws-solutions-constructs/resources/lib/template-writer-custom-resource and inspect the PutObject path alongside the reported CDK asset bucket policy and Lambda logs. Reproduce with the listed CDK and Solutions Constructs versions, and verify that the custom resource returns TemplateOutputKey after the upload succeeds under the bucket's encryption requirements.

Written by the indexing model from the issue text.