What version of ogen are you using?

v1.4.1

Can this issue be reproduced with the latest version?

Yes (checked on v1.10.1)

What did you do?

Created an entiry with a single oneOf reference:

ObjA:
  type: object

ObjB:
  type: object
  oneOf:
    - $ref: "#/components/schemas/ObjA"

What did you expect to see?

Successful generation

What did you see instead?

func (s *ObjB) encodeFields(e *jx.Encoder) {
    s.OneOf.encodeFields(e)
}

Message: s.OneOf.encodeFields undefined (type ObjBSum has no field or method encodeFields)