Response parameters bug fix

[jormaechea]

Fixed a typo to fix the bug.

Closes #756

[dnalborczyk]

Thank you @jormaechea !

[dnalborczyk]

hey @jormaechea same here, do you have a simple scenario in form of a serverless.yml and a handler file (which fails without your fix) I could add to the tests?

[jormaechea]

Sure @dnalborczyk. This simple case does not work properly:

serverless.yml

service: TestService

provider:
  name: aws
  runtime: nodejs10.x
  region: us-east-1

functions:
  HelloWorldApi:
    handler: index.handler
    description: Hello World API
    events:
      - http:
          integration: lambda
          path: hello-world
          method: get
          responses:
            default:
              responseModels:
                application/json;charset=UTF-8: Empty
              responseParameters:
                method.response.header.x-foo: "integration.response.body.foo"
              responseTemplates:
                application/json;charset=UTF-8: ""
              statusCode: 200

plugins:
  - serverless-offline

index.js

module.exports.handler = async () => {
	return {
		foo: 'bar'
	};
};

It prints this warning in the console:

Serverless: Warning: while processing responseParameter "0": "method.response.header.x-foo"
Serverless: Offline plugin only supports "method.response.header.PARAM_NAME" left-hand responseParameter. Found "0" instead. Skipping.
Serverless: If you think this is an issue with the plugin please submit it, thanks!
Serverless: https://github.com/dherault/serverless-offline/issues

[dnalborczyk]

thanks again @jormaechea !