Allow configuration of OAuth2LoginAuthenticationFilter.authenticationResultConverter

Expected Behavior

OAuth2LoginAuthenticationFilter has a authenticationResultConverter property (link to code). It would be nice if we could set it through HttpSecurity.oauth2Login configuration during SecurityFilterChain registration

Current Behavior

It seems there is no way to set it to a custom converter through HttpSecurity builder. I tried registering a custom Converter bean implementation for the same type but it wasn't auto-wired through the setter method. I guess oauth2 login configurer doesn't attempt to find a converter bean during initialization.

Context

What I am trying to do is, capture some request parameters during the oauth login authorization flow and then access them after successful authentication. I have a custom OAuth2AuthorizationRequestResolver which appends additional attributes to the OAuth2AuthorizationRequest. After successful authentication, OAuth2LoginAuthenticationFilter obtains a OAuth2LoginAuthenticationToken and converts it to a OAuth2AuthenticationToken. It seems, there is no way to access the OAuth2AuthorizationRequest afterwards. So I need to have a custom converter there.

I use a BeanPostProcessor as a workaround to set the converter which seems to be working fine. I just thought it would be nice to have it configurable as OAuth2LoginAuthenticationFilter already have a public setter for that property.

Start with OAuth2LoginAuthenticationFilter.java, especially its authenticationResultConverter setter, then trace the HttpSecurity.oauth2Login configuration entry point used during SecurityFilterChain registration. Determine where that setting can be exposed through the OAuth2 login configuration. Done means a custom converter can be supplied through HttpSecurity.oauth2Login rather than a BeanPostProcessor workaround.