[PHP] oneOf at nullable objects: not uses FQCN

Description

The config used to generate the code contains this:
"invokerPackage": "Base\Sub",

In case of a nullable object property for example:

        prop1:
          nullable: true
          oneOf:
            - $ref: '#/components/schemas/Prop1'

The generated PHP code will contain the following:

    protected static $swaggerTypes = [
        'courier' => 'OneOfProp1'];

whereas it should contain this:

    protected static $swaggerTypes = [
        'courier' => '\Base\Sub\OneOfProp1'];

This causes the ObjectSerializer::deserialize to fail because the OneOfProp1 can't be found/loaded.

Swagger-codegen version

3.0.26

Command line used for generation

swagger-codegen generate -i apiContract/api.yaml -l php -c swaggerCodegenConfig.json -o ../generated/api-client

Suggest a fix/enhancement

Use the FQCN

Start by locating the PHP generator template or entry point that produces the swaggerTypes mapping, then inspect how nullable oneOf properties are handled. Re-run the provided swagger-codegen command with the example configuration and verify that the generated type uses the invokerPackage FQCN and that ObjectSerializer::deserialize can load it.