Merge pull request #28967 from terminux

* pr/28967:
  Polish "Check for the presence of Spring Security"
  Check for the presence of Spring Security

Closes 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.
@@ -58,6 +58,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
+import org.springframework.security.web.server.csrf.CsrfToken;
 import org.springframework.util.MimeType;
 import org.springframework.util.unit.DataSize;
 import org.springframework.web.servlet.resource.ResourceUrlEncodingFilter;
@@ -279,7 +280,7 @@ DataAttributeDialect dialect() {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnClass({ SpringSecurityDialect.class })
+	@ConditionalOnClass({ SpringSecurityDialect.class, CsrfToken.class })
 	static class ThymeleafSecurityDialectConfiguration {
 
 		@Bean