Flatten HttpSecurity.oauth2()

Fixes gh-5715

samples/boot/authcodegrant/src/integration-test/java/org/springframework/security/samples/OAuth2AuthorizationCodeGrantApplicationTests.java

@@ -147,10 +147,9 @@ public class OAuth2AuthorizationCodeGrantApplicationTests {
 				.authorizeRequests()
 					.anyRequest().authenticated()
 					.and()
-				.oauth2()
-					.client()
-						.authorizationCodeGrant()
-							.accessTokenResponseClient(this.accessTokenResponseClient());
+				.oauth2Client()
+					.authorizationCodeGrant()
+						.accessTokenResponseClient(this.accessTokenResponseClient());
 		}
 		// @formatter:on
 

samples/boot/authcodegrant/src/main/java/sample/config/SecurityConfig.java

@@ -41,8 +41,7 @@ public class SecurityConfig extends WebSecurityConfigurerAdapter {
 				.and()
 			.formLogin()
 				.and()
-			.oauth2()
-				.client();
+			.oauth2Client();
 	}
 
 	@Bean