oneOf object property results in uncompilable code

[mberndt123]

Hey here,

Here's a schema that results in uncompilable code:

openapi: 3.0.0
info:
  title: XXXXXX
  version: 0.1.0
paths: {}
components:
  schemas:
    X:
      type: object
      properties:
        links:
          oneOf:
            - type: object

The code generated looks like this:

/*
 * This file was generated by guardrail (https://github.com/guardrail-dev/guardrail).
 * Modifications will be overwritten; instead edit the OpenAPI/Swagger spec file.
 */
package swagger.definitions
import cats.syntax.either._
import io.circe.syntax._
import cats.instances.all._
import _root_.swagger.Implicits._
case class X(links: Option[X.Links] = None)
object X {
  implicit val encodeX: _root_.io.circe.Encoder.AsObject[X] = {
    _root_.io.circe.Encoder.AsObject.instance[X](a => _root_.io.circe.JsonObject.fromIterable(_root_.scala.Vector(("links", a.links.asJson))))
  }
  implicit val decodeX: _root_.io.circe.Decoder[X] = new _root_.io.circe.Decoder[X] { final def apply(c: _root_.io.circe.HCursor): _root_.io.circe.Decoder.Result[X] = for (v0 <- c.downField("links").as[Option[X.Links]]) yield X(v0) }
}

As you can see, case class X contains a field of type Option[X.Links], but there is no Links type defined in the X object.

Obviously the oneOf thing is useless here and when I just write links: { "type": "object" } instead it works. But I'm using a schema provided by an API vendor that contains constructs like this, and I'd like to be able to use it as-is.