[BUG] [Java] oneOf inception provides wrong output in toJson

Description

to json functions gives the wrong output

openapi-generator version

7.5.0 -> no library defined

OpenAPI declaration file content or url

The following Yaml

    pt:
      type: object
      additionalProperties:
        nullable: true
        oneOf:
          - $ref: "#/components/schemas/mv"
          - $ref: "#/components/schemas/pi"
          - type: array
            items:
              oneOf:
                - $ref: "#/components/schemas/mv"
                - $ref: "#/components/schemas/pi"
    mv:
      oneOf:
        - $ref: "#/components/schemas/sv"
        - type: array
          items:
            $ref: "#/components/schemas/sv"

    sv:
      oneOf:
        - type: number
          format: double
        - type: string

    pi:
      type: object
      properties:
        value:
          $ref: "#/components/schemas/mv"
      additionalProperties:
        $ref: "#/components/schemas/pt"

With the following Java

		Pi pi = new Pi().value(new Mv(new Sv(1d)));
		pi.putAdditionalProperty("key", new Pi().value(new Mv(new Sv(0d))));

		pi.toJson();
		log.debug("{}", pi.toJson());

gives:

{"value":{"instance":1.0,"isNullable":false,"schemaType":"oneOf"},"key":{"value":{"instance":0.0,"isNullable":false,"schemaType":"oneOf"}}}

Where i would expect

{"value": 1.0,"key":{"value": 0.0}}

Reproduce the report by generating the Java models from the supplied OpenAPI YAML with openapi-generator 7.5.0, then inspect the generated Pi, Mv, and Sv classes and their toJson behavior. Compare the serialized output with the expected JSON for the nested oneOf values; done means the generated output omits the internal oneOf metadata and represents the numeric values correctly.