Add java 11 support for #987 (o-t) (#1051)

* Use java 11

* Use .of
- Replace Arrays.asList with List.of
- Replace HashSet<>(List.of()) with Set.of

* Formatting

thread-pool/src/main/java/com/iluwatar/threadpool/App.java

@@ -60,22 +60,22 @@ public class App {
     LOGGER.info("Program started");
 
     // Create a list of tasks to be executed
-    List<Task> tasks = new ArrayList<>();
-    tasks.add(new PotatoPeelingTask(3));
-    tasks.add(new PotatoPeelingTask(6));
-    tasks.add(new CoffeeMakingTask(2));
-    tasks.add(new CoffeeMakingTask(6));
-    tasks.add(new PotatoPeelingTask(4));
-    tasks.add(new CoffeeMakingTask(2));
-    tasks.add(new PotatoPeelingTask(4));
-    tasks.add(new CoffeeMakingTask(9));
-    tasks.add(new PotatoPeelingTask(3));
-    tasks.add(new CoffeeMakingTask(2));
-    tasks.add(new PotatoPeelingTask(4));
-    tasks.add(new CoffeeMakingTask(2));
-    tasks.add(new CoffeeMakingTask(7));
-    tasks.add(new PotatoPeelingTask(4));
-    tasks.add(new PotatoPeelingTask(5));
+    List<Task> tasks = List.of(
+            new PotatoPeelingTask(3),
+            new PotatoPeelingTask(6),
+            new CoffeeMakingTask(2),
+            new CoffeeMakingTask(6),
+            new PotatoPeelingTask(4),
+            new CoffeeMakingTask(2),
+            new PotatoPeelingTask(4),
+            new CoffeeMakingTask(9),
+            new PotatoPeelingTask(3),
+            new CoffeeMakingTask(2),
+            new PotatoPeelingTask(4),
+            new CoffeeMakingTask(2),
+            new CoffeeMakingTask(7),
+            new PotatoPeelingTask(4),
+            new PotatoPeelingTask(5));
 
     // Creates a thread pool that reuses a fixed number of threads operating off a shared
     // unbounded queue. At any point, at most nThreads threads will be active processing