[nodejs-server] discriminator not taken into account?

Description

When using a discriminator I expect that the generated code will use the discriminator field to determine which class it needs to map to.
It does not seem to do so.

Swagger-codegen version

v3

Swagger declaration file content or url

openapi: 3.0.3
info:
  version: 1.0.0
  title: pet-demo
  description: Pet Demo

paths:
  /pets:
    patch:
      requestBody:
        content:
          application/json:
            schema:
              oneOf:
                - $ref: '#/components/schemas/Cat'
                - $ref: '#/components/schemas/Dog'
              discriminator:
                propertyName: petType
      responses:
        '200':
          description: Updated
components:
  schemas:
    Pet:
      type: object
      properties:
        name:
          type: string
        petType:
          type: string
      required:
      - name
      - petType
    Cat:
      description: A representation of a cat
      allOf:
      - $ref: '#/components/schemas/Pet'
    Dog:
      description: A representation of a dog
      allOf:
      - $ref: '#/components/schemas/Pet'
      - type: object
        properties:
          packSize:
            type: integer
            format: int32
            description: the size of the pack the dog is from
            default: 0
            minimum: 0
        required:
        - packSize

Command line used for generation

docker run --rm -v ${PWD}:/local swaggerapi/swagger-codegen-cli-v3 generate -i /local/openapi.yaml -l nodejs-server -o /local/out/node

Steps to reproduce

Running the curl command below with a petType Dog should attempt to match the object with the Dog class which should cause a failure since the Dog class requires a packSize property.
However, this returns 200 OK which leads me to believe that it matches the Cat object which does not require any additional properties.
That means that the discriminator field is not being used to map the object to the correct class.

curl --location --request PATCH 'http://127.0.0.1:8080/pets' \
--header 'Content-Type: application/json' \
--data-raw '{
  "name": "charlie",
  "petType": "Dog"
}'

Reproduce the issue with openapi.yaml using the nodejs-server Docker generation command and the provided PATCH curl request, then inspect the generated server output for discriminator handling. Done means a Dog payload missing packSize is mapped to Dog and rejected rather than returning 200 OK.