[BUG] [JAVA] items: allOf: [$ref: Pet] does not generate List<@Valid Pet> #25113

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

'List<@Valid>` not generated for items using allOf.

 listStubb:
    type: array
    items:
      allOf:
        - $ref: '#/components/schemas/Stubb'

Expected generation:
private List<@Valid Stubb> listStubb;

Actual generation
private List<Stubb> listStubb;

The allOf is needed if vendorExtensions ared used. The swagger parser does not allow items with $ref and x- vendorExtensions.
For example:

listStubb:
  type: array
  items:
    allOf:
      - $ref: '#/components/schemas/Stubb'
    x-field-extra-annotation: '@NotEmpty' 

openapi-generator version

7.25.0

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: allOf+$ref+annotation
  version: 1.0.0
components:
  schemas:
    Stubb:
      type: object
      properties:
        name:
          type: string
    SampleModel:
      type: object
      properties:
        listStubb:
          type: array
          items:
            allOf:
              - $ref: '#/components/schemas/Stubb'

Generation Details

openapi-generator-cli generate -g spring --skip-validate-spec -i issue_25113.yaml

Steps to reproduce

Build the sample and look at the generate List of Stubb. It lacks @Valid

Related issues/PRs

#25049 highlight the issue

Suggest a fix

Detect the pattern items + allOf of a single $ref