I noticed that requestBody.required wasn't being respected and requests without a body were failing with an [EOF] error even though required was set to false.

This PR is a tentative fix to this issue. It certainly works as my API now behaves according to the spec and it fails without a body only if required: true

I was wondering if we should also do:

var body *{{$opid}}{{.NameTag}}RequestBody

That would mean that if the body isn't present we would correctly send a nil object down to the server implementation but I am concerned that would lead to lots of panics in existing services for users that hadn't been paying attention to the fact that required: false is the default behavior when not set.

Thoughts?