Description

When using the Quarkus OpenAPI Generator extension with GitLab API's project_id path parameter (which accepts URL-encoded project paths), the extension either:

1. Doesn't encode slashes when passed unencoded values, causing 404 errors
2. Double-encodes already-encoded values, also causing 404 errors

This makes it impossible to use GitLab's project path format (e.g., mygroup/myproject/backend) with the generated REST client.

Problem

GitLab's API accepts project_id as either:

• A numeric project ID (e.g., 12345)
• A URL-encoded project path (e.g., mygroup%2Fmyproject%2Fbackend for mygroup/myproject/backend)

Current Behavior

Scenario 1: Passing unencoded project path

Workflow input data:

{
  "project_id": "mygroup/myproject/backend"
}

Workflow action:

- name: "getMergeRequestDetails"
  functionRef:
    refName: getMergeRequest
    arguments:
      project_id: .project_id
      merge_request_iid: 123

Expected URL: /api/v4/projects/mygroup%2Fmyproject%2Fbackend/merge_requests/123
Actual URL: /api/v4/projects/mygroup/myproject/backend/merge_requests/123
Result: 404 Not Found (GitLab interprets the slashes as path segments)

Scenario 2: Passing pre-encoded project path

Workflow input data:

{
  "project_id": "mygroup%2Fmyproject%2Fbackend"
}

Workflow action:

- name: "getMergeRequestDetails"
  functionRef:
    refName: getMergeRequest
    arguments:
      project_id: .project_id
      merge_request_iid: 123

Expected URL: /api/v4/projects/mygroup%2Fmyproject%2Fbackend/merge_requests/123
Actual URL: /api/v4/projects/mygroup%252Fmyproject%252Fbackend/merge_requests/123
Result: 404 Not Found (The %2F is encoded again to %252F, making it unrecognizable)

Expected Behavior

The OpenAPI Generator should:

1. Encode special characters in path parameters (e.g., / → %2F)
2. Detect already-encoded values and skip encoding them (avoid double encoding)

OR provide a configuration option to control encoding behavior per path parameter.

OpenAPI Specification

Here's the relevant GitLab API spec showing the project_id parameter usage:

openapi: 3.0.0
info:
  title: GitLab Repository Automation API
  version: 1.0.0
paths:
  /api/v4/projects/{project_id}/merge_requests/{merge_request_iid}:
    get:
      summary: Get merge request details
      operationId: getMergeRequest
      parameters:
        - name: project_id
          in: path
          required: true
          schema:
            type: string
        - name: merge_request_iid
          in: path
          required: true
          schema:
            type: integer
      responses:
        '200':
          description: Success
        '404':
          description: Not Found