title: Swagger : TypeError: Failed to fetch
body: <p>I am trying to define a simple API which is pretty much an healthcheck.
  My problem is that the requests is correct, the answer I receive from the server is correct, but it is not displayed by swagger : <a href="https://imgur.com/a/pgTL4" rel="nofollow noreferrer">http://imgur.com/a/pgTL4</a></p>
  
  <p>Here's what the answer I get (which is correct) : <a href="https://imgur.com/a/qPLZy" rel="nofollow noreferrer">http://imgur.com/a/qPLZy</a> and the HTTP status is 200 : <a href="https://imgur.com/a/LmIpf" rel="nofollow noreferrer">http://imgur.com/a/LmIpf</a></p>
  
  <p>Also,I have defined the HTTP status 200 and 500 : <a href="https://imgur.com/a/eaxfr" rel="nofollow noreferrer">http://imgur.com/a/eaxfr</a></p>
  
  <p>Would anyone have a hint ? Thanks.</p>