Add access to Router in AuthHandlerFactory

[Mateusz512]

Is your feature request related to a problem? Please describe.
When attempting to implement OAuth2 based security, with OOTB Vert.x functionalities, I've encountered a need to register custom routing when creating the handler.

Describe the solution you'd like
AuthHandlerFactory should have the possibility to register some custom routing, required for example for an OAuth2 callback.

Describe alternatives you've considered
It is possible to implement it as two different OpenAPI3 based endpoints, but it breaks the isolation between security logic and routing logic (business logic).

[malaskowski]

How about using callbacks option as a part of the defined OpenAPI3 operation?
You can then define a custom callback for OAuth2.
There is also quite extensive explanation with examples available in the Swagger spec: https://swagger.io/docs/specification/callbacks/

[Mateusz512]

How about using callbacks option as a part of the defined OpenAPI3 operation?
You can then define a custom callback for OAuth2.
There is also quite extensive explanation with examples available in the Swagger spec: https://swagger.io/docs/specification/callbacks/

Looks nice, but the catch is that with current implementation of OAuth2 flow in Vert.x I need to specifically call OAuth2AuthHandlerImpl#setupCallback which takes Route as a param. Under the hood it is explicitly registering a handler for retrieving the authentication code and exchanging it for access token:

    ...
    route.handler(ctx -> {
      // Handle the callback of the flow
      ...
    });

    // the redirect handler has been setup so we can process this
    // handler has full oauth2
    bearerOnly = false;
    callback = route;

    return this;
  }

The bearerOnly = false is crucial as well, it prevents the inital request from being revoked right away (yep, this field is private 😒 )