$ref sibling fields cause validation to fail

[urcheraus]

This schema passes validation with v0.135.0 but fails to validate with versions v0.136.0..v0.149.0 (latest at time of writing).

openapi: 3.0.0
info:
  version: 0.0.0
  title: $ref with siblings example
paths: {}
components:
  schemas:
    Schema1:
      type: object
      properties:
        p:
          description: Some text
          $ref: '#/components/schemas/Schema2'
    Schema2:
      type: string

The error message is Validation error: invalid components: schema "Schema1": extra sibling fields: [description]

The relevant section of the OpenAPI 3.0.0 specification states that

any properties added SHALL be ignored

so I believe the description here is allowed by the spec and should not cause a validation failure.

--

The schemas I'm working with have a lot of description and example fields for referenced schemas, which is useful documentation for humans even if it is ignored by programs.

[fenollp]

Well I guess you're right! I'm not at my desk for a few more weeks however. In the meantime I suggest you open a PR changing the v3.0 behavior.

[urcheraus]

I don't think this is just for v3.0, versions 3.2.0 and 3.1.2 have similar "any properties added SHALL be ignored" statements.

I'll leave making a PR for someone more familiar with this codebase.