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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

allVars does not contain the properties when the properties are on the same level as the allOf
Simlar to Object3 in issue_16797.yaml

openapi-generator version

7.4

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: OpenAPI definition
  version: '1.0'
paths:
  /pets:
    get:
      summary: Get all pets
      operationId: getAllPets
      responses:
        default:
          description: ok
components:
  schemas:
    Pet:
      type: object
      properties:
        petType:
          type: string    
      discriminator:
        propertyName: petType
    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
      type: object
      properties:
        name:
          type: string

Ps: the issue also exists if there is no discriminator

Generation Details

Spring generator (probably all generators that support inheritance)

Steps to reproduce

use this templates/pojo.mustache for demonstration

/**
allVars
=======
{{#allVars}}{{name}} {{/allVars}}

vars
=======
{{#vars}}{{name}} {{/vars}}

parentVars
========
{{#parentVars}}{{name}} {{/parentVars}}
*/

openapi-generator-cli generate -g spring -i allvarSample.yaml -o out -t templates

Cat.java has an invalid allVars. It should contain name.

/**
allVars
========
petType 

vars
========
name 

parentVars
========
 petType
*/

Related issues/PRs

Suggest a fix

Add a normalizer that transforms the model into

    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            name:
               type: string