fix violations

Author: JensMyParcel

src/main/java/com/example/devopstraining/DevopsTrainingApplication.java

@@ -4,9 +4,13 @@
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 @SpringBootApplication
-public class DevopsTrainingApplication {
+public final class DevopsTrainingApplication {
 
-    public static void main(String[] args) {
+    private DevopsTrainingApplication() {
+        // Private constructor to prevent instantiation
+    }
+
+    public static void main(final String[] args) {
         SpringApplication.run(DevopsTrainingApplication.class, args);
     }
 }

src/main/java/com/example/devopstraining/controller/HelloController.java

@@ -7,15 +7,15 @@
 
 @RestController
 @RequestMapping("/api")
-public class HelloController {
+public final class HelloController {
 
     @GetMapping("/hello")
     public String hello() {
         return "Hello, DevOps Training!";
     }
 
     @GetMapping("/hello/{name}")
-    public String helloWithName(@PathVariable String name) {
+    public String helloWithName(@PathVariable final String name) {
         return "Hello, " + name + "!";
     }