[BUG][KOTLIN] oneOf does not generate type hierarchy correctly

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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 having an endpoint that returns R being oneOf a or b (or more), the generated classes for A and B do not implement the generated interface which is generated for R and therefore the deserialization with Jackson fails.

openapi-generator version

7.14.0 (gradle plugin)

OpenAPI declaration file content or url

---
openapi: 3.0.1
info:
  title: some
  version: 1.0.0
servers:
  - url: http://localhost:8080
    description: Local server


paths:
  "/someEndponint":
    get:
      summary: Get the specified device job of a single device
      description: |
        Obtain a specified device job of a single device

      operationId: someEndpoint
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                oneOf:
                  - "$ref": "#/components/schemas/A"
                  - "$ref": "#/components/schemas/B"
                discriminator:
                  propertyName: jobType
                  mapping:
                     A: "#/components/schemas/A"
                     B: "#/components/schemas/B"
components:
  schemas:
    A:
      type: object
      properties:
        jobType:
          type: string
        propertyA:
          type: string

    B:
      type: object
      properties:
        jobType:
          type: string
        propertyB:
          type: string

Generation Details

here is the plugin configuration:

tasks.register<GenerateTask>("openApiGenerateV2Client") {
        generatorName = "kotlin" 
        inputSpec = "$projectDir/src/main/resources/static/v2/open-api-docs.yaml"
        outputDir = "${layout.buildDirectory.get()}/generated/client/"
        configOptions =
            mapOf(
                "library" to "jvm-spring-restclient",
                "serializationLibrary" to "jackson",
                "useSpringBoot3" to "true",
            )
    }

Steps to reproduce

have a server that implement specified interface, call the client method, it produces the following Exception:

Caused by: com.fasterxml.jackson.databind.exc.InvalidTypeIdException: Could not resolve type id 'A' as a subtype of `...SomeEndpoint200Response`: Class `...A` not subtype of `...SomeEndpoint200Response`
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 1, column: 12]
	at com.fasterxml.jackson.databind.exc.InvalidTypeIdException.from(InvalidTypeIdException.java:43)
	at com.fasterxml.jackson.databind.DeserializationContext.invalidTypeIdException(DeserializationContext.java:2096)
	at com.fasterxml.jackson.databind.jsontype.impl.TypeDeserializerBase._findDeserializer(TypeDeserializerBase.java:198)
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:150)
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:135)
	at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserializeWithType(AbstractDeserializer.java:262)
	at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:74)
	at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342)

Here the generated Code

data class A (

    @get:JsonProperty("jobType")
    val jobType: kotlin.String? = null,

    @get:JsonProperty("propertyA")
    val propertyA: kotlin.String? = null

)

data class B (

    @get:JsonProperty("jobType")
    val jobType: kotlin.String? = null,

    @get:JsonProperty("propertyB")
    val propertyB: kotlin.String? = null

) 

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "jobType", visible = true)
@JsonSubTypes(
)

interface SomeEndpoint200Response {

    @get:JsonProperty("jobType")
    val jobType: kotlin.String?
    @get:JsonProperty("propertyA")
    val propertyA: kotlin.String?
    @get:JsonProperty("propertyB")
    val propertyB: kotlin.String?

}

Related issues/PRs

Suggest a fix

How the code should be generated (note, the Java generator creates a similar structure):

data class A : SomeEndpoint200Response (

    @get:JsonProperty("jobType")
    override val jobType: kotlin.String? = null,

    @get:JsonProperty("propertyA")
    val propertyA: kotlin.String? = null

)

data class B : SomeEndpoint200Response (

    @get:JsonProperty("jobType")
   override val jobType: kotlin.String? = null,

    @get:JsonProperty("propertyB")
    val propertyB: kotlin.String? = null

) 

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "jobType", visible = true)
@JsonSubTypes(
)

interface SomeEndpoint200Response {

    @get:JsonProperty("jobType")
    val jobType: kotlin.String?

}

Reproduce the issue with the supplied OpenAPI declaration, Kotlin Gradle configuration, and generated classes. Start by tracing the Kotlin generator's model generation for oneOf responses and compare it with the shown Java-style structure. Done means generated A and B types participate in SomeEndpoint200Response and Jackson deserializes the example response without InvalidTypeIdException.