V2 - Incorrect nullability for RequestBody Content property

[baywet]

Request body Content is declared as

IDictionary<string, OpenApiMediaType>?

I believe it should be

IDictionary<string, OpenApiMediaType?>?

Reasoning: in the spec none of the properties of media type are required, so you could perfectly have the request body be simply

content:
- application/octet-stream:

Validated with @darrelmiller on an internal conversation.

[baywet]

After working on that for a little while I realized that it's the wrong thing to do:

• not emitting anything after the key leads to invalid JSON.
• emitting null is invalid according to the JSON schema.
• emitting an empty object is not symmetrical, which would force us to do advanced object comparison on deserialization, which would become problematic if a property with a default for media type ever gets introduced.
• if the consumer is worried about the memory consumption, they can always leverage a static instance to avoid duplicating the memory footprint across multiple operations/path items when using the dom
• we have additional work that will be more impactful for performance

[mikekistler]

@darrelmiller This strikes me as yet another case of wanting to use "nullable" to mean "optional". Some day I hope we figure out how to express "optional" in C# that everyone understands.