Issue with self-referencing entites

[Fifi31]

Describe the bug
When a sub-entity of a request has a field of its own type, the resulting schema doesn't reference itself. It works well if the request (the top-level type) references itself, but not for sub-entities.

To Reproduce
Playground

type SubEntity struct {
	Self *SubEntity `json:"self"`
}
type Req struct {
	SubEntity *SubEntity `json:"subentity"`
	Self      *Req       `json:"self"`
}

func main() {
	reflector := openapi3.Reflector{}
	reflector.Spec = &openapi3.Spec{Openapi: "3.1.0"}

	putOp := openapi3.Operation{}

	reflector.SetRequest(&putOp, Req{}, http.MethodPut)
	reflector.Spec.AddOperation(http.MethodPut, "/things/{id}", putOp)

	schema, err := reflector.Spec.MarshalYAML()
	if err != nil {
		log.Fatal(err)
	}

	// Req schema references itself on self field, but SubEntity schema has no reference on self field
	fmt.Println(string(schema))
}

Expected behavior
components.schemas.SubEntity.properties.self should have a $ref field with the value '#/components/schemas/SubEntity'.

Also SubEntity.self has nullable set as true but I am not sure if it is normal, as Req.self has not.

[vearutop]

Now should be fixed in master, thanks for reporting this!