openapi-generator: [BUG] Using `allOf` and `$ref` generates an `object` in the python model when it should be a `string`

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?

Description

openapi-generator version

Docker CLI latest

OpenAPI declaration file content or url

BankTransferCreateRequest:
  title: BankTransferCreateRequest
  type: object
  description: BankTransferCreateRequest defines the request schema for `/bank_transfer/create`
  properties:
    access_token:
      description: Some Description
      allOf:
        - $ref: '#/components/schemas/AccessToken'
 
AccessToken:
  title: AccessToken
  type: string
  description: The access token associated with the Item data is being requested for.

/bank_transfer/create:
  post:
    operationId: bankTransferCreate
    requestBody:
      required: true
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/BankTransferCreateRequest'

Generation Details

$(OPENAPI_GENERATOR_LATEST) -g python -i local/$(OPENAPI_FILE) -o local/$(OUTPUT_FOLDER)/generated-python

Steps to reproduce

Run the generator, try accessing the BankTransferCreateRequest model. See that access_token is object instead of string.

return {
    'access_token': (object,),  # noqa: E501
}

Related issues/PRs

Suggest a fix