oneOf support in request body schema for NSwag.Generation.AspNetCore

According to the checked list item in #945, oneOf should be supported. Specifically what we need is oneOf support for requestBody schemas, as shown in the first example here:

paths:
  /pets:
    patch:
      requestBody:
        content:
          application/json:
            schema:
              oneOf:
                - $ref: '#/components/schemas/Cat'
                - $ref: '#/components/schemas/Dog'

We’re having difficulties implementing it, though, as we find no way to decorate our ASP.NET Core code to generate an OpenAPI document with requestBody.content.application/json.schema.oneOf defined.

Instead, NSwag attempts to generate an OpenAPI document with duplicate path definitions, causing the following code to be invoked and exception to be thrown:

https://github.com/RicoSuter/NSwag/blob/085e8aeb95e4f1723f956fa6137bbc07bd5527a6/src/NSwag.Generation.AspNetCore/AspNetCoreOpenApiDocumentGenerator.cs#L260-L263

Ideas and pointers in the right direction would be highly appreciated.

[asbjornu]

@NullableInt, as pointed out by @RicoSuter on Twitter let’s discuss whether we can use inheritance to make this work somehow.

[asbjornu]

@RicoSuter, if we were to fork and implement this ourselves, would you accept a pull request? Also, could you please point us in the right direction on where and how you’d like to see this implemented in the existing source code?