Polish "Check for the presence of Spring Security"

See gh-28967

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,8 +58,6 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
-import org.springframework.security.core.context.ReactiveSecurityContextHolder;
-import org.springframework.security.web.reactive.result.view.CsrfRequestDataValueProcessor;
 import org.springframework.security.web.server.csrf.CsrfToken;
 import org.springframework.util.MimeType;
 import org.springframework.util.unit.DataSize;
@@ -282,8 +280,7 @@ public class ThymeleafAutoConfiguration {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnClass({ SpringSecurityDialect.class, ReactiveSecurityContextHolder.class,
-			CsrfRequestDataValueProcessor.class, CsrfToken.class })
+	@ConditionalOnClass({ SpringSecurityDialect.class, CsrfToken.class })
 	static class ThymeleafSecurityDialectConfiguration {
 
 		@Bean