OAuth2Flow
Typed OAuth 2.0 authorization-code flow.
Created by oauth2 and installed with Route.install or Application.install. Visiting loginPath triggers a redirect to the OAuth provider; the provider returns to the callback route.
Unauthenticated requests to the callback path or loginPath redirect to the OAuth provider.
For session-backed route protection, use oauth2Session instead. The two factory functions are alternatives: oauth2 handles login entirely in the callback handler, while oauth2Session exposes OAuth2SessionFlow.session for use with authenticateWith.