diff --git a/java-spring-boot-demo/src/main/java/com/example/demo/DemoController.java b/java-spring-boot-demo/src/main/java/com/example/demo/DemoController.java
index 61a5075..420e076 100644
--- a/java-spring-boot-demo/src/main/java/com/example/demo/DemoController.java
+++ b/java-spring-boot-demo/src/main/java/com/example/demo/DemoController.java
@@ -7,8 +7,8 @@ import org.springframework.web.bind.annotation.RestController;
 public class DemoController {
 
     @RequestMapping("/")
-    public Object root() {
-        return null;
+    public String root() {
+        return "";
     }
 
 }