fix: property with nested allOf

[AlexVarchuk]

What/Why/How?

fix: #2079

Reference

Testing

openapi: 3.0.3
info:
  version: 0.0.1
  title: Test API
servers: []
tags:
  - name: Order
paths:
  /orders:
    summary: Product ordering
    post:
      tags:
        - Order
      summary: Create order
      description: |
        Create an order
      operationId: createProductOrder
      requestBody:
        $ref: "#/components/requestBodies/Order"
      responses:
        "201":
          $ref: "#/components/responses/OrderCreated"
components:
  schemas:
    ProductOfferingId:
      description: Original description for type `ProductOfferingId` which should have
        been overridden
      type: string
      example: SOME_PRODUCT
    AccountId:
      description: >
        Original description for type `AccountId` which should have been
        overridden (type with `readOnly: true`)
      type: string
      readOnly: true
      example: "123456789"
    ProductOrder:
      description: |
        Represents an order
      type: object
      properties:
        offeringId:
          description: |
            Overidden description for `offeringId`
          allOf:
            - $ref: "#/components/schemas/ProductOfferingId"
        billingAccountId:
          description: >
            Overridden description for `billingAccountId` (type with `readOnly:
            false`)
          readOnly: false
          allOf:
            - $ref: "#/components/schemas/AccountId"
  requestBodies:
    Order:
      required: true
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/ProductOrder"
  responses:
    OrderCreated:
      description: Created
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/ProductOrder"

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