Resolve issue where the parent schema has multiple discriminator mappings and each child schema also declares its all discriminator mapping

[joelrosario]

What:

The following schema was not handled correctly:

Vehicle:
  allOf:
    - ${'$'}ref: '#/components/schemas/VehicleType'
    - type: object
      properties:
        seatingCapacity:
          type: integer
  discriminator:
    propertyName: "type"
    mapping:
      "car": "#/components/schemas/Transmission"
      "bike": "#/components/schemas/SideCar"

Transmission:
  allOf:
    - ${'$'}ref: '#/components/schemas/Vehicle'
    - type: object
      requried:
        - gearType
      properties:
        gearType:
          type: string
  discriminator:
    propertyName: "type"
    mapping:
      "car": "#/components/schemas/Transmission"

Note that car is declared both in the parent Vehicle schema and the child Transmission schema.

Checklist:

• Documentation added to the README.md OR link to PR on https://github.com/specmatic/specmatic-documentation
• Tests
• Sonar Quality Gate