The following example `serverless.yml` fails to deploy on localstack:

```yaml
service: "localtest"

provider:
  name: "aws"
  runtime: "nodejs10.x"

functions:
  hello:
    handler: "handler.hello"
    
resources:
  Resources:
    ApiGatewayRestApi:
      Type: "AWS::ApiGateway::RestApi"
      Properties:
        Name: "${self:provider.stage}-${self:service}"
    GatewayResponseDefault400:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "DEFAULT_4XX"
        ResponseTemplates:
          application/json: '{"errors":[{"message":"Custom text."}]}'
    GatewayResponseUnauthorized:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "UNAUTHORIZED"
        ResponseTemplates:
          application/json: '{"errors":[{"message":"Custom text!", "extra":"Some extra info"}]}'
    GatewayResponseDefault500:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "DEFAULT_5XX"
        ResponseTemplates:
          application/json: '{"errors":[{"message":$context.error.messageString}]}'
    GatewayResponseIntegrationTimeout:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "INTEGRATION_TIMEOUT"
        ResponseTemplates:
          application/json: '{"errors":[{"message":$context.error.messageString}]}'

plugins:
- "serverless-localstack"

custom:
  localstack:
    stages:
      - "local"
```

The error on the localstack end is `Exception: CloudFormation deployment for resource type ApiGateway::GatewayResponse not yet implemented`.
parsed_result = result if isinstance(result, dict) else json.loads(result)
            parsed_result = common.json_safe(parsed_result)
            response.status_code = int(parsed_result.get('statusCode', 200))
            response.headers.update(parsed_result.get('headers', {}))
            try:
                if isinstance(parsed_result['body'], dict):
                    response._content = json.dumps(parsed_result['body'])
                else:
                    response._content = parsed_result['body']
            except Exception:
                response._content = '{}'
            return response
        else:
            msg = 'API Gateway action uri "%s" not yet implemented' % uri
            LOGGER.warning(msg)
            return make_error(msg, 404)
    elif integration['type'] == 'HTTP':
        function = getattr(requests, method.lower())
        if isinstance(data, dict):
            data = json.dumps(data)
        result = function(integration['uri'], data=data, headers=headers)
        return result
    else:
        msg = ('API Gateway integration type "%s" for method "%s" not yet implemented' %
               (integration['type'], method))
        LOGGER.warning(msg)
        return make_error(msg, 404)
    return 200
UPDATE_APIGATEWAY = ProxyListenerApiGateway()