Append "*/*" To The defaultContentTypes List

If a default content type is set in the ContentNegotiationConfigurer, endpoints that don't return that type can return a 406. I've attached a very simple example.

demo.zip

Bug Explanation:
For an endpoint that produces some other content type (example in attached code is text/plain):

• Making a request without an Accept header will result in a 406
• Making a request with an Accept header of '*/*' will result in a 406
• Making a request with an Accept header of 'garbage/garbage,*/*' will result in 200

This behavior is wrong -- All of these should return a 200. Setting a default content type should not cause endpoints to result in 406. At a minimum, accept headers of 'garbage/garbage,*/*' and '*/*' should behave the same..

Extra explanation
Why are we setting a default content type? Because for nearly all endpoints, we want the returned content to be available as XML or JSON, and default to JSON if nothing else is specified.