Provide Smithy models for default API Gateway errors

Whenever we deploy our services using API Gateway from AWS, there are errors that we have no control over (as described here). The details of those errors are needed in order to allow the proper deserialization within the client SDKs. We have tried to solve this with two different approaches, although without success:

1. By defining the model for them ourselves, but we have not been able to find what are the possible X-Amzn-ErrorType HTTP headers that are being sent by API Gateway. The closest possibility can apparently be found here.
2. By overriding the X-Amzn-ErrorType HTTP header using the OpenAPI extension x-amazon-apigateway-gateway-responses. That caused the header to be sent two times containing our override value BadRequestException and the default value IncompleteSignatureException from API Gateway (as shown in the attached image). The client SDK does not seem to like that, and simply ignore our value.

Is is possible for AWS to provide the Smithy models only of those default API Gateway errors (similar to this here), please?

[gosar]

@eduardomourar @DanielBauman88 are you unblocked with the change to js repo?

On the Smithy side, we’d still want to add a protocol test for this, so other language SDKs can also support this. So leaving this issue open for that followup.

[DanielBauman88]

This does unblock me.

Appreciate you keeping this open - would be great to have the same support for all the supported languages!