[BUG][4.3.1] The schema name is substituted with the path (under certain circumstances)

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used? 4.3.1
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

I switched from version 4.3.0 to 4.3.1 because I really need this fix #5830

With v4.3.1 the schema name is substituted with the path in the generated code.
The issue occurs under very particular circumstances but unfortunately it made all my API not working properly anymore. The circumstances are:

• the main api (main.yaml) references a path located in another file (e.g., ./endpoints/orders_id.yaml) and containing a path param
• for a response schema the path references a model located in an other file.

Please have a look to the example below to better understand the issue.

openapi-generator version

I am using v4.3.1.

It is not a problem of a specific generator. I am having the issue also with spring generator for instance.

I believe the issue is a regression.

OpenAPI declaration file content or url

./main.yaml
The main api file references a path located in ./endpoints/orders_id.yaml.

openapi: 3.0.2
info:
  title: order-api-spec
  version: 0.1.1

paths:
  "/orders/{id}":
    $ref: "./endpoints/orders_id.yaml#/paths/~1orders~1{id}"

---

./endpoints/orders_id.yaml
The GET /orders/{id} returns a model Order located in another file.

openapi: 3.0.2
info:
  title: orders-api-spec
  version: ignored

paths:
  "/orders/{id}":
    get:
      parameters:
        - in: path
          name: id
          description: Id of the target resource
          required: true
          schema:
            type: integer
            format: int64
      tags:
        - order
      responses:
        200:
          description: Ok
          content:
            application/json:
              schema:
                $ref: "../models/order.yaml#/components/schemas/Order"

---

./models/order.yaml

openapi: 3.0.2
info:
  title: orders-api-spec
  version: ignored

paths: {}

components:
  schemas:
    Order:
      type: object
      properties:
        name:
          type: string

Command line used for generation

$ java -jar openapi-generator-cli.jar generate -g openapi-yaml -i main.yaml -o ./out

Result with v4.3.0 (OK)

openapi: 3.0.2
info:
  title: cxp-api-spec
  version: ignored
servers:
- url: /
paths:
  /orders/{id}:
    get:
      parameters:
      - description: Id of the target resource
        in: path
        name: id
        required: true
        schema:
          format: int64
          type: integer
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Order'
          description: Ok
      tags:
      - order
components:
  schemas:
    Order:
      example:
        name: name
      properties:
        name:
          type: string
      type: object

Result with v4.3.1 (KO)

Issues:

• the model referenced in the response is actually the path: #/components/schemas/~1orders~1{id}
• the Order schema is missing in #/components/schemas

openapi: 3.0.2
info:
  title: cxp-api-spec
  version: ignored
servers:
- url: /
paths:
  /orders/{id}:
    get:
      parameters:
      - description: Id of the target resource
        in: path
        name: id
        required: true
        schema:
          format: int64
          type: integer
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/~1orders~1{id}'
          description: Ok
      tags:
      - order
components:
  schemas: {}

Steps to reproduce

• download and extract the attached zip -> example.zip
• cd into it
• run the cli generator with args generate -g openapi-yaml -i main.yaml -o ./out

---

Start by running the documented CLI command with main.yaml and the attached example, then compare the generated output with the v4.3.0 and v4.3.1 results. Inspect the references from endpoints/orders_id.yaml to models/order.yaml; done means the generated response points to Order and components/schemas contains the Order schema.