Polish servlet OAuth2 docs landing page

Issue gh-14758

docs/modules/ROOT/pages/servlet/oauth2/index.adoc

@@ -491,7 +491,7 @@ With the above configuration, the application now supports two additional endpoi
 ====
 The presence of the `openid` scope in the above configuration indicates that OpenID Connect 1.0 should be used.
 This instructs Spring Security to use OIDC-specific components (such as `OidcUserService`) during request processing.
-Without this scope, Spring Security will use OAuth2-specific components (such as `OAuth2UserService`) instead.
+Without this scope, Spring Security will use OAuth2-specific components (such as `DefaultOAuth2UserService`) instead.
 ====
 
 [[oauth2-client-access-protected-resources]]
@@ -708,7 +708,7 @@ class MessagesController(private val webClient: WebClient) {
 			.uri("http://localhost:8090/messages")
 			.attributes(clientRegistrationId("my-oauth2-client"))
 			.retrieve()
-			.toEntityList(Message::class.java)
+			.toEntityList<Message>()
 			.block()!!
 	}
 
@@ -933,7 +933,7 @@ class MessagesController(private val webClient: WebClient) {
 		return webClient.get()
 			.uri("http://localhost:8090/messages")
 			.retrieve()
-			.toEntityList(Message::class.java)
+			.toEntityList<Message>()
 			.block()!!
 	}
 
@@ -953,7 +953,7 @@ This is because it can be derived from the currently logged in user.
 === Enable an Extension Grant Type
 
 A common use case involves enabling and/or configuring an extension grant type.
-For example, Spring Security provides support for the `jwt-bearer` grant type, but does not enable it by default because it is not part of the core OAuth 2.0 specification.
+For example, Spring Security provides support for the `jwt-bearer` and `token-exchange` grant types, but does not enable them by default because they are not part of the core OAuth 2.0 specification.
 
 With Spring Security 6.2 and later, we can simply publish a bean for one or more `OAuth2AuthorizedClientProvider` and they will be picked up automatically.
 The following example simply enables the `jwt-bearer` grant type:
@@ -1356,12 +1356,18 @@ Spring Security automatically resolves the following generic types of `OAuth2Acc
 * `OAuth2ClientCredentialsGrantRequest` (see `DefaultClientCredentialsTokenResponseClient`)
 * `OAuth2PasswordGrantRequest` (see `DefaultPasswordTokenResponseClient`)
 * `JwtBearerGrantRequest` (see `DefaultJwtBearerTokenResponseClient`)
+* `TokenExchangeGrantRequest` (see `DefaultTokenExchangeTokenResponseClient`)
 
 [TIP]
 ====
 Publishing a bean of type `OAuth2AccessTokenResponseClient<JwtBearerGrantRequest>` will automatically enable the `jwt-bearer` grant type without the need to <<oauth2-client-enable-extension-grant-type,configure it separately>>.
 ====
 
+[TIP]
+====
+Publishing a bean of type `OAuth2AccessTokenResponseClient<TokenExchangeGrantRequest>` will automatically enable the `token-exchange` grant type without the need to <<oauth2-client-enable-extension-grant-type,configure it separately>>.
+====
+
 [[oauth2-client-customize-rest-operations]]
 === Customize the `RestOperations` used by OAuth2 Client Components
 
@@ -1427,6 +1433,15 @@ public class SecurityConfig {
 		return accessTokenResponseClient;
 	}
 
+	@Bean
+	public OAuth2AccessTokenResponseClient<TokenExchangeGrantRequest> tokenExchangeAccessTokenResponseClient() {
+		DefaultTokenExchangeTokenResponseClient accessTokenResponseClient =
+			new DefaultTokenExchangeTokenResponseClient();
+		accessTokenResponseClient.setRestOperations(restTemplate());
+
+		return accessTokenResponseClient;
+	}
+
 	@Bean
 	public RestTemplate restTemplate() {
 		// ...
@@ -1482,6 +1497,14 @@ class SecurityConfig {
 		return accessTokenResponseClient
 	}
 
+	@Bean
+	fun tokenExchangeAccessTokenResponseClient(): OAuth2AccessTokenResponseClient<TokenExchangeGrantRequest> {
+		val accessTokenResponseClient = DefaultTokenExchangeTokenResponseClient()
+		accessTokenResponseClient.setRestOperations(restTemplate())
+
+		return accessTokenResponseClient
+	}
+
 	@Bean
 	fun restTemplate(): RestTemplate {
 		// ...
@@ -1561,6 +1584,14 @@ public class SecurityConfig {
 			new JwtBearerOAuth2AuthorizedClientProvider();
 		jwtBearerAuthorizedClientProvider.setAccessTokenResponseClient(jwtBearerAccessTokenResponseClient);
 
+		DefaultTokenExchangeTokenResponseClient tokenExchangeAccessTokenResponseClient =
+			new DefaultTokenExchangeTokenResponseClient();
+		tokenExchangeAccessTokenResponseClient.setRestOperations(restTemplate());
+
+		TokenExchangeOAuth2AuthorizedClientProvider tokenExchangeAuthorizedClientProvider =
+			new TokenExchangeOAuth2AuthorizedClientProvider();
+		tokenExchangeAuthorizedClientProvider.setAccessTokenResponseClient(tokenExchangeAccessTokenResponseClient);
+
 		OAuth2AuthorizedClientProvider authorizedClientProvider =
 			OAuth2AuthorizedClientProviderBuilder.builder()
 				.authorizationCode()
@@ -1574,6 +1605,7 @@ public class SecurityConfig {
 					.accessTokenResponseClient(passwordAccessTokenResponseClient)
 				)
 				.provider(jwtBearerAuthorizedClientProvider)
+				.provider(tokenExchangeAuthorizedClientProvider)
 				.build();
 
 		DefaultOAuth2AuthorizedClientManager authorizedClientManager =
@@ -1644,6 +1676,12 @@ class SecurityConfig {
 		val jwtBearerAuthorizedClientProvider = JwtBearerOAuth2AuthorizedClientProvider()
 		jwtBearerAuthorizedClientProvider.setAccessTokenResponseClient(jwtBearerAccessTokenResponseClient)
 
+		val tokenExchangeAccessTokenResponseClient = DefaultTokenExchangeTokenResponseClient()
+		tokenExchangeAccessTokenResponseClient.setRestOperations(restTemplate())
+
+		val tokenExchangeAuthorizedClientProvider = TokenExchangeOAuth2AuthorizedClientProvider()
+		tokenExchangeAuthorizedClientProvider.setAccessTokenResponseClient(tokenExchangeAccessTokenResponseClient)
+
 		val authorizedClientProvider = OAuth2AuthorizedClientProviderBuilder.builder()
 			.authorizationCode()
 			.refreshToken { refreshToken ->
@@ -1656,6 +1694,7 @@ class SecurityConfig {
 				password.accessTokenResponseClient(passwordAccessTokenResponseClient)
 			}
 			.provider(jwtBearerAuthorizedClientProvider)
+			.provider(tokenExchangeAuthorizedClientProvider)
 			.build()
 
 		val authorizedClientManager = DefaultOAuth2AuthorizedClientManager(