Describe the bug
Continuation of #153 (comment).

Basically I am trying to set up swagger on my Spring Boot webflux app. It's deployed behind a reverse proxy. I already set up all necessary things like server.forward-headers-strategy=framework and the x-forwarded-* headers. It's working well on MVC app.

To Reproduce
Steps to reproduce the behavior:

Spring Boot 3.5.5
SpringDoc 2.8.9

1. Set up Spring boot webflux app.
2. Enable swagger UI from SpringDoc.
3. Set up a reserve proxy that directs particular prefix to the app, eg http://localhost/gtw/swagger-ui/ --> http://localhost:8081/swagger-ui/

Actual behavior

• When browsing swagger-ui, it loads swagger-config from the wrong path, eg http://localhost/v3/api-docs/swagger-config.

• Interestingly, when I hit http://localhost/gtw/v3/api-docs/swagger-config manually, it contain the correct config with additional prefix, eg

  {
   "configUrl": "/gtw/v3/api-docs/swagger-config",
   "oauth2RedirectUrl": "http://localhost/gtw/swagger-ui/oauth2-redirect.html",
   "urls": [
   {
   "url": "/gtw/v3/api-docs",
   "name": "Gateway API"
   },
   {
   "url": "/gtw/v3/api-docs/main-service",
   "name": "Main Service"
   }
   ],
   "validatorUrl": ""
  }

• When I remove server.forward-headers-strategy=framework, the config doesn't contain prefix, eg

   {
   "configUrl": "/v3/api-docs/swagger-config",
   "oauth2RedirectUrl": "http://localhost/swagger-ui/oauth2-redirect.html",
   "urls": [
   {
   "url": "/v3/api-docs",
   "name": "Gateway API"
   },
   {
   "url": "/v3/api-docs/main-service",
   "name": "Main Service"
   }
   ],
   "validatorUrl": ""
   }

Expected behavior

• When browsing swagger-ui, it should load swagger-config from the correct path, eg http://localhost/gtw/v3/api-docs/swagger-config.

Screenshots
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Additional context
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