public class AuthorizationCodeRequestRedirectFilter
This Filter initiates the authorization code grant flow by redirecting
the end-user's user-agent to the authorization server's Authorization Endpoint.
It uses an AuthorizationRequestUriBuilder to build the OAuth 2.0 Authorization Request,
which is used as the redirect URI to the Authorization Endpoint.
The redirect URI will include the client identifier, requested scope(s), state, response type, and a redirection URI
which the authorization server will send the user-agent back to (handled by AuthorizationCodeAuthenticationFilter)
once access is granted (or denied) by the end-user (resource owner).