[KOTLIN] allOf doesn't generate $ref

[Lena-Gadzieva]

Description

When generating with kotlin-client a class like this:

Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - properties:
            hunts:
              type: boolean
            age:
              type: integer

ignores $ref and only generates attributes from properties

Swagger-codegen version

3.0.61

Related issues/PRs

Similar issue was raised before: https://github.com/swagger-api/swagger-codegen/issues/12241