oneOf not generating union class properties Typescript-Angular

Description

I am using the example provided in the tests for oneOf. Once I try to generate for typescript-angular I get the three classes:

// apple.ts
export interface Apple { 
    kind?: string;
}

// banana.ts
export interface Banana { 
    count?: number;
}

// fruit.ts
import { Apple } from './apple';
import { Banana } from './banana';

export type Fruit = Apple | Banana;

As you can see the color property of fruit is missing.

openapi-generator version

I was using version 4.0.1 with the docker version.

Docker image used was:

openapitools/openapi-generator-cli@sha256:d67438016ccf3067655eb12ce23aab2b6f3e89f916cd153ae9874251af82b3e2

OpenAPI declaration file content or url

openapi: 3.0.1
info:
   title: fruity
   version: 0.0.1
paths:
   /:
      get:
         responses:
            '200':
               description: desc
               content:
                  application/json:
                     schema:
                        $ref: '#/components/schemas/fruit'
components:
   schemas:
      fruit:
         title: fruit
         properties:
            color:
               type: string
         oneOf:
            - $ref: '#/components/schemas/apple'
            - $ref: '#/components/schemas/banana'
      apple:
         title: apple
         type: object
         properties:
            kind:
               type: string
      banana:
         title: banana
         type: object
         properties:
            count:
               type: number

Command line used for generation

docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli@sha256:d67438016ccf3067655eb12ce23aab2b6f3e89f916cd153ae9874251af82b3e2 generate \
-i /local/input.yaml \
-g typescript-angular \
-c /local/config.json \
-o /local

Content of config.json is:

{
    "apiPackage": "api",
    "ngVersion": "6"
}

Steps to reproduce

Execute the test file using the provided command.

Reproduce the issue with input.yaml, config.json, and the typescript-angular generator using the command provided. Compare the generated fruit.ts with the schema and example in the issue; done means the color property is represented in the generated union type or its related output.