Handling 204 response codes

[darrelmiller]

Where an OpenAPI operation only includes 204 in its successful responses, the generated method should be declared to effectively return void.

'/DoTheThing':
    POST:
      responses:
        '204':
          description: An empty response
      x-csharp: Task DoTheThing.PostAsync(...);    

If at runtime, the server returns a different 2XX with a body, then we should read the body and then discard it. Failing to read the body will hang the server.

When a operation is expected to return a value, but instead returns a 204 at runtime (whether described or not), the returned value should be null.

'/nullableSimpleObject':
    get:
      responses:
        '200':
          description: A response with an object type response
          content: { "application/json": { schema: { $ref: "#/components/schemas/simpleObject" }}}
        '204':
          description: A response with an object type but with null value
      x-csharp: Task<SimpleObject> GetAsync(...);    

[baywet]

fixed with #1457 and other pull requests. interestingly enough Java requires you to close the response but not to read it. Dotnet and Go to read and close. JavaScript to read without closing.