fix(openapi): don't apply the global name converter to the generated document

[soyuka]

Problem

#8306 fixed Reference serialization ($ref) by wiring serializer.mapping.class_metadata_factory and serializer.name_converter.metadata_aware into the OpenAPI serializer's inline ObjectNormalizer, so that #[SerializedName('$ref')] on Reference::getRef() is honored.

Side effect (reported by @thomas-hiron in #8306): serializer.name_converter.metadata_aware carries framework.serializer.name_converter as its fallback converter (see FrameworkExtension, which sets argument 1 of that service to the configured name converter). So a project configured with:

framework:
    serializer:
        name_converter: serializer.name_converter.camel_case_to_snake_case

now gets the whole OpenAPI document run through that converter, producing snake_case keys: operation_id, extension_properties, request_bodies, security_schemes, authorization_url… which break openapi-generator-cli:

-attribute paths.'/api/article'(get).extension_properties is unexpected

Fix

Reference::getRef()'s #[SerializedName('$ref')] is the only serialization metadata the OpenAPI models rely on. Use a dedicated MetadataAwareNameConverter built with the class metadata factory only (no fallback). SerializedName is still honored; the globally configured converter no longer leaks into the document.

Tests

New tests/Functional/OpenApiNameConverterTest.php boots a kernel configuring the global camelCase_to_snake_case converter and asserts:

• OpenAPI keys stay camelCase (operationId, no operation_id / extension_properties / request_bodies / security_schemes)
• #[SerializedName('$ref')] still emits $ref

Verified failing on the buggy wiring, passing with the fix. Full OpenApiTest + OpenApiNormalizerTest suites green (28 tests, 268 assertions).

[thomas-hiron]

Fix confirmed, thanks!!