以2.2.1.BUILD-SNAPSHOT 为基准，适配Greenwich版本的Spring Cloud

spring-cloud-alibaba-examples/sentinel-example/sentinel-core-example/pom.xml

@@ -30,6 +30,10 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-thymeleaf</artifactId>
+        </dependency>
 
         <!--<dependency>-->
         <!--<groupId>com.alibaba.csp</groupId>-->