Which content type to prefer for swagger docs?

Suppose this API:

``` haskell
type SampleAPI = "sample" :> Get '[JSON, FormUrlEncoded, XML] Sample
```

Should we use a `body` param with Swagger Schema or `formData` params?
With swagger spec it does not seem to make sense having both.
It also appears we can't have duplicate paths with different params.

I tend to think that we should just pick the first content type of the list (if any).
The other option might be to pick one of the most precedence (e.g. prefer `JSON` then `FormUrlEncoded`).

Start by tracing how the SampleAPI content types are translated into Swagger Schema and formData parameters. Compare the handling of JSON, FormUrlEncoded, and XML, including duplicate paths, and define the expected single-content-type behavior before making a change. Done means the selected representation is consistent with the Swagger specification.

Written by the indexing model from the issue text.