[Python][test] oneOf with overlapping types

Created by: jirikuncar

tl;dr Shows a serialization problem of oneOf models in python-experimental with overlapping types.

Minimal specification

Two models with overlapping field definition of named enum type.

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
      oneOf:
        - $ref: "#/components/schemas/apple"
        - $ref: "#/components/schemas/banana"
    appleColor:
      type: string
      enum:
        - yellow
        - green
        - red
    apple:
      title: apple
      type: object
      properties:
        kind:
          type: string
        color:
          $ref: '#/components/schemas/appleColor'
    bananaColor:
      type: string
      enum:
        - yellow
        - green
    banana:
      title: banana
      type: object
      properties:
        count:
          type: number
        color:
          $ref: '#/components/schemas/bananaColor'

Problem

The generated model contains all fields and the overlapping field has wrong type.

    @cached_property
    def openapi_types():
        """..."""
        return {
            'kind': (str,),  # noqa: E501
            'color': (banana_color.BananaColor,),  # noqa: E501
            'count': (float,),  # noqa: E501
        }

     # ...

     attribute_map = {
        'kind': 'kind',  # noqa: E501
        'color': 'color',  # noqa: E501
        'count': 'count',  # noqa: E501
    }

This prevents deserialization of {"kind": "sweet", "color": "red"} response.

How do I get expected behavior?

Simply remove definition of openapi_types and attribute_map and let the oneOf models do the job.

PR checklist

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cc @sebastien-rosset