[BUG] url-encoded-request Parameter with extensible enum

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 generating an API Controller using url-encoded-request Parameter and extensible enums, the annotations are wrong and input parameter cannot be read

openapi-generator version

id "org.openapi.generator" version "7.7.0"

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  version: 1.0.0
  title: FBDE API
paths:
  /v1/my/api:
    post:
      description: My description
      operationId: myApi
      requestBody:
        required: true
        content:
          application/x-www-form-urlencoded:
            schema:
              properties:
                myParam:
                  description: My parameter description
                  allOf:
                    - $ref: '#/components/schemas/MyExtensibleEnum'
                      # TODO multiple allOf do not work with generator plugin < 6.5+
                      # https://github.com/OpenAPITools/openapi-generator/issues/10010#issuecomment-1482326673
                    - type: string
                      x-extensible-enum:
                        - NOT_SPECIFIED
      responses:
        '200':
          description: ok
components:
  schemas:
    MyExtensibleEnum:
      type: string
      x-extensible-enum:
        - ONE
        - TWO
        - THREE

Generation Details

openApiGenerate  {
	generatorName = "spring"
	inputSpec = openapi.yaml
	configOptions = [
			dateLibrary: "java11",
			interfaceOnly: "true",
			hideGenerationTimestamp: "true",
			oas3: "true",
			useTags: "true",
			documentationProvider: "springdoc",
			openApiNullable: "false",
			containerDefaultToNull: "false"
	]
}

Steps to reproduce

./gradlew clean openApiGenerate

Generatred code has following annotations:

@Parameter(name = "myParam", description = "My parameter description") @Valid @RequestPart(value = "myParam", required = false) String myParam,

It should be like this:

@Parameter(name = "myParam", description = "My parameter description") @Valid @RequestParam(value = "myParam", required = false) String myParam,

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/10010

Suggest a fix

Start with the openapi.yaml reproduction and run ./gradlew clean openApiGenerate using the Spring generator configuration shown. Inspect the generated API controller for the application/x-www-form-urlencoded parameter and compare its annotations with the expected @RequestParam output. Done means the generated parameter uses @RequestParam while retaining the documented name, validation, and required setting.