[Core] oneOf schema properties

[lwlee2608]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?

Description

vars missing from model if they are given oneOf rule

openapi-generator version

4.2.2-SNAPSHOT

OpenAPI declaration file content or url

    Area:
      type: object
      oneOf:
        - required:
          - tacs
        - required:
          - areaCode
      properties:
        tacs:
          type: array
          items:
            $ref: '#/components/schemas/Tac'
          minItems: 1
        areaCode:
            $ref: '#/components/schemas/AreaCode'

Steps to reproduce

checkout from here
./run.sh

The generated code won't compile because Area is missing properties tacs and areaCode

Suggest a fix

call addVars from schema.properties here
https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java#L1939

[spacether]

This other pr also attempts to fix this issue
#4482

[lwlee2608]

@spacether I see, the fix is also identical. And it comes with tests, nice.

[jimschubert]

@lwlee2608 can you run your spec through an online validator? oneOf should be an array of Schemas, but what you've presented as an example shouldn't be valid. Additionally, oneOf technically shouldn't have any additional properties besides discriminator, although I've seen this numerous times.

For example, using this spec:

openapi: "3.0.1"
info:
   title: title
   version: 0.0.1
paths:
   /:
      get:
         responses:
            '200':
               description: none
               content:
                  application/json:
                     schema:
                        $ref: '#/components/schemas/Area'
components:
   schemas:
      AreaCode:
         title: AreaCode
         type: object
         properties:
            value:
               type: string
      Tac:
         type: object
         properties:
            count:
               type: number
            type:
               type: string
      Area:
         type: object
         oneOf:
         - required:
            - tacs
         - required:
            - areaCode
         properties:
         tacs:
            type: array
            items:
               $ref: '#/components/schemas/Tac'
            minItems: 1
         areaCode:
               $ref: '#/components/schemas/AreaCode'

You should see multiple errors in OpenAPI Generator's validation:

openapi-generator validate -i ~/Documents/sam.yml --recommend
Validating spec (/Users/jim/Documents/sam.yml)
Errors:
	-attribute components.schemas.Area.properties is not of type `object`
	-attribute components.schemas.Area.areaCode is unexpected
	-attribute components.schemas.Area.tacs is unexpected
Warnings:
	-Unused model: Tac
	-Unused model: AreaCode

[error] Spec has 3 errors.

You've ticked the validation TODO item in the description, but my above minimal spec fails validation in the linked validator:

[lwlee2608]

@jimschubert
I have run the validator before it is valid. The schema file I was using can be found here

The difference is AreaCode and Tac is defined as primitive string in my case

[lwlee2608]

full-blown original 3gpp schema file can be found here

[spacether]

Should be fixed by #4482