pass empty json {} on post

[fehguy]

from swagger-api/swagger-ui#873 we must pass either nothing or an empty JSON when posting to an operation and specifying content-type application/json

[saadmufti]

The original issue was actually about surrounding an enum with quotes when used as a POST body parameter and the content-type is application/json

[fehguy]

OK digging into this more, here's some feedback.

Currently the content-type is NOT set if there is no body passed in the request. This is good and bad--namely it will not set Content-Type to application/json if you don't pass an object. The bad is that because the content type isn't set, the server has to guess. And depending on the server implementation, this is potentially a problem.

First we need to pass Content-Type regardless of presence of a body. Then we can detect that it's application/json and set it to an empty object.

[fehguy]

see a6b2142