Downloaded Swagger Pet Store (Simple) from swagger.io editor page and did a mvn jetty:run
When opening up DevTools on Chrome and exercising a GET, I don't see the header Content-Type field being set.
This is on the GET /pets{id}
OK, found the root cause of this problem thanks to wing328 on the swagger codegen project on github.
It turns out that at the top of our yaml definition file we have:
consumes: - application/json
That causes all generated controller methods to expect application/json on content-type. This breaks GET, DELETE, and PATCH api calls which in our case do not have any payload.