Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue? -> see add test showcasing ref property siblings being lost in OpenAPI 3.1 #20303
• Have you validated the input using an OpenAPI validator (example)? The correctness of the snippets I'm trying to parse were discussed in Parser ignore readOnly/writeOnly on property with $ref swagger-api/swagger-parser#2036
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output? -> see the test
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Starting with OpenAPI 3.1, it is allowed for $ref-objects to have sibling properties and those sibling properties should not be lost. A simple example would be:

components:
  schemas:
    ModelWithTitledProperties:
      properties:
        refProperty:
          type: string
          title: Ref-Property-Title
          $ref: '#/components/schemas/RefObject'
      type: object
    RefObject:
      type: string

Expected: when generating code, I have access to refProperty's title field.
Reality: The value of title (and other fields, such as description) are lost.

For example, if I try to generate TypeScript code that includes a model's title using a custom template (but the issue is not TypeScript-specific):

export const {{classname}}Meta = {
{{#vars}}
    {{name}}: {
        title: `{{{title}}}`,
        description: `{{{description}}}`
    },
{{/vars}}
} as const;

this works for regular properties, but title and description are always empty for properties that include a $ref.

openapi-generator version

7.10.0 (actually latest master, d29196a).
As far as I understand, this is not a regression, but just a yet undetected bug for OpenAPI 3.1 schemas.

Steps to reproduce

I opened a complimentary pull request that adds a test case showcasing the problem: #20303

Suggest a fix

Best lead I found while debugging was that ModelUtils#unaliasSchema seems to just 100% forward the $ref'ed schema if it detects a ref that doesn't fall into one of the special cases like isObjectSchema(...).