[BUG][kotlin-server] Kotlin Server Generator Does Not Support UUID

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 next spec:

definitions:
  UuidTest:
    type: object
    required:
      - uuidReq
    properties:
      uuidReq:
        type: string
        format: uuid
        example: 72f98069-206d-4f12-9f12-3d1e525a8e84
      uuidNoReq:
        type: string
        format: uuid
        example: 72f98069-206d-4f12-9f12-3d1e525a8e84

the generator generates next code:

@Serializable
data class UuidTest(
  val uuidReq: UUID,
  var uuidNoReq: UUID,
)

which causes next compilation error after running gradle assemble:

Details: kotlinx.serialization compiler plugin internal error: unable to transform declaration, see cause
...
Caused by: java.lang.IllegalStateException: Serializer for element of type java.util.UUID? has not been found
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerSearchUtilKt.findTypeSerializerOrContext(SerializerSearchUtil.kt:84)

To solve this issue is it should generate next kotlin code with the annotation @Contextual from kotlinx.serialization package:

@Serializable
data class UuidTest(
  @Contextual
  val uuidReq: UUID,
  @Contextual
  var uuidNoReq: UUID,
)

openapi-generator version

7.4.0

Generation Details

openapi-generator generate -i uuid-test.yaml -g kotlin-server

Suggest a fix

Start with the kotlin-server generator entry point and reproduce the issue using the shown openapi-generator command and uuid-test.yaml specification. Inspect how UUID properties are rendered in the generated Kotlin data class, then run gradle assemble and verify both required and optional UUID fields compile with the expected contextual serialization handling.