Using attribute routing ignores the removal of XmlFormatter MediaTypes
<p>I have a web api with several controllers, which use convention-based routing.
However, for one controller I want to use attribute routing, but as soon as I put the RoutePrefix and Route attributes on my controller class and methods, Chrome returns XML instead of JSON, along with the message</p>

<blockquote>
  <p>This XML file does not appear to have any style information associated
  with it. The document tree is shown below.</p>
</blockquote>

<p>The controller:</p>

<pre><code>[RoutePrefix("WebVerslaggeving")]
public class WebVerslaggevingController : ApiController
{
    [Route("GetProjectVoorwaardeDocumenten/{projectId:int}/{webVoorwaardeId:int}")]
    public IHttpActionResult GetProjectVoorwaardeDocumenten(int projectId, int webVoorwaardeId)
    {
        var ftpPath = string.Format(@"{0}/Voorwaarden/{1}/", projectId, webVoorwaardeId);

        var fileList = GetFilesFromFolder($@"ftp://{_ftpServer}/{ftpPath}", recursively: true);

        return Ok(fileList);
    }
}
</code></pre>

<p>In my WebApiConfig, I included these lines:</p>

<pre><code>config.MapHttpAttributeRoutes();
config.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
</code></pre>

<p>But apparently that's not working with attribute routing. As soon as I remove the attributes, JSON is returned.</p>

<p>What am I missing?</p>