Hi Stephen and George,
The problem is the the current version always tries to add a Swagger.json to the end of the url, as that is what the spec required. Unfortunately, most services/frameworks do not follow that part of the spec.
I already removed that restriction but it is only scheduled to be included on the next major version of the platform.
For the current version you will need to use the Swagger Proxy component.The component allows you to add a url to any swagger documentation and it will create a url ending with Swagger.json for you.