Fix sonar error in leaderfollowers module #3233

Author: sanurah

Diff for: leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java

@@ -67,12 +67,13 @@ public static void main(String[] args) throws InterruptedException {
   /** Start the work, dispatch tasks and stop the thread pool at last. */
   private static void execute(WorkCenter workCenter, TaskSet taskSet) throws InterruptedException {
     var workers = workCenter.getWorkers();
-    var exec = Executors.newFixedThreadPool(workers.size());
-    workers.forEach(exec::submit);
-    Thread.sleep(1000);
-    addTasks(taskSet);
-    exec.awaitTermination(2, TimeUnit.SECONDS);
-    exec.shutdownNow();
+    try (var exec = Executors.newFixedThreadPool(workers.size())) {
+      workers.forEach(exec::submit);
+      Thread.sleep(1000);
+      addTasks(taskSet);
+      exec.awaitTermination(2, TimeUnit.SECONDS);
+      exec.shutdownNow();
+    }
   }
 
   /** Add tasks. */