binding parameter default value with allOf schema

[podhmo]

Default value binding does not work well when parameter schema has allOf.

For example, when I set a custom default value while referencing the schema with $ref, we can write it using allOf in OpenAPI 3.x.

components:
  schemas:
    TaskSortEnum:
      enum:
        - createdAt
        - -createdAt
        - updatedAt
        - -updatedA
paths:
  /tasks:
    get:
      description: ""
      operationId: ListTask
      parameters:
        - in: query
          name: sort
          schema:
            allOf:
              - $ref: '#/components/schemas/TaskSortEnum'
              - default: -createdAt

But, this doesn't work in the current implementation.

Related oapi-codegen's issue is here.

• "merging two sets of defaults is undefined" is occured when allOf with default value oapi-codegen/oapi-codegen#1379