[BUG] [Kotlin][kotlin-spring] Multi-level interface inheritance doesn't work

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When using multi-level inheritance, the kotlin-spring generator produces non-compiling code.

Geometry.kt:32:13 'type' hides member of supertype 'GeoJsonObject' and needs 'override' modifier
GeometryElement.kt:31:13 'type' hides member of supertype 'Geometry' and needs 'override' modifier

MultiPoint.kt:25:86 Unresolved reference: Type -> must be GeometryElement.Type instead of MultiPoint.Type

openapi-generator version

$ openapi-generator-cli version
7.7.0

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Sample API
  description: API description in Markdown.
  version: 1.0.0
paths:
  /points:
    get:
      summary: Returns all points.
      description: Optional extended description in Markdown.
      responses:
        200:
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PageOfPoints'

components:
  schemas:
    PageOfPoints:
      required:
        - content
      allOf:
        - $ref: "#/components/schemas/Page"
        - properties:
            content:
              type: array
              default: []
              items:
                $ref: "#/components/schemas/Points"

    Points:
      type: object
      required:
        - points
      properties:
        points:
          $ref: "./common/GeoJson.yaml#/components/schemas/MultiPoint"

    Page:
      type: object
      required:
        - number
        - size
        - totalPages
        - totalElements
      properties:
        number:
          type: integer
          format: int32
          default: 0
          description: Current page number
        size:
          type: integer
          format: int32
          default: 0
          description: Number of elements per page
        totalPages:
          type: integer
          format: int32
          default: 0
          description: Number of total pages
        totalElements:
          type: integer
          format: int64
          default: 0
          description: Total number of elements

https://app.swaggerhub.com/apis/OlivierMartineau/GeoJSON/1.0.1

Generation Details

openapi-generator-cli generate -g kotlin-spring -i openapi.yaml --additional-properties documentationProvider=none --additional-properties interfaceOnly=true

Steps to reproduce

1. run generation command above
2. run gradle build

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/16946
https://github.com/OpenAPITools/openapi-generator/issues/18206

Suggest a fix

As a temporary workaround, it might be possible to bypass the issue using custom mustache templates, but I'm not familiar with them.

Run the listed openapi-generator-cli command with the supplied OpenAPI declaration, then inspect the generated Geometry.kt, GeometryElement.kt, and MultiPoint.kt files. Trace the kotlin-spring generator path that produces these declarations. Done means the generated project builds with Gradle without the reported override and unresolved Type errors.