anchor.diff:  
   The primary role of the `OAuth2AuthorizationRequestResolver` is to resolve an `OAuth2AuthorizationRequest` from the provided web request.
   The default implementation `DefaultOAuth2AuthorizationRequestResolver` matches on the (default) path `/oauth2/authorization/{registrationId}` extracting the `registrationId` and using it to build the `OAuth2AuthorizationRequest` for the associated `ClientRegistration`.
  +
  +Given the following Spring Boot 2.x properties for an OAuth 2.0 Client registration:
  +
  +[source,yaml]
  +----
  +spring:
  +  security:
  +    oauth2:
  +      client:
  +        registration:
  +          okta:
  +            client-id: okta-client-id
  +            client-secret: okta-client-secret
  +            authorization-grant-type: authorization_code
  +            redirect-uri: "{baseUrl}/authorized/okta"
  +            scope: read, write
  +----
  +
  +A request with the base path `/oauth2/authorization/okta` will initiate the Authorization Request redirect by the `OAuth2AuthorizationRequestRedirectFilter` and ultimately start the Authorization Code grant flow.
  +
  +[NOTE]
  +The `AuthorizationCodeOAuth2AuthorizedClientProvider` is an implementation of `OAuth2AuthorizedClientProvider` for the Authorization Code grant,
  +which also initiates the Authorization Request redirect by the `OAuth2AuthorizationRequestRedirectFilter`.
   
   
   ===== Customizing the Authorization Request
  
positive.code: 
  The primary role of the `OAuth2AccessTokenResponseClient` is to exchange an authorization grant credential for an access token credential at the Authorization Server's Token Endpoint.
  
  The default implementation of `OAuth2AccessTokenResponseClient` for the `authorization_code` grant is `DefaultAuthorizationCodeTokenResponseClient`, which uses a `RestOperations` for exchanging an authorization code for an access token at the Token Endpoint.
  
  The `DefaultAuthorizationCodeTokenResponseClient` is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.
  
  
negative.code: [source,java]
  ----
  @Controller
  public class OAuth2ClientController {
  
  	@RequestMapping("/")
  	public String index(@RegisteredOAuth2AuthorizedClient("okta") OAuth2AuthorizedClient authorizedClient) {
  		OAuth2AccessToken accessToken = authorizedClient.getAccessToken();
  
  		...
  
  		return "index";
  	}
  }
  ----
  