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

commander/src/main/java/com/iluwatar/commander/Service.java

@@ -43,7 +43,7 @@ public abstract class Service {
   public ArrayList<Exception> exceptionsList;
   private static final Random RANDOM = new Random();
   private static final String ALL_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
-  private static final Hashtable<String, Boolean> USED_IDS = new Hashtable<String, Boolean>();
+  private static final Hashtable<String, Boolean> USED_IDS = new Hashtable<>();
 
   protected Service(Database db, Exception...exc) {
     this.database = db;

commander/src/test/java/com/iluwatar/commander/RetryTest.java

@@ -45,9 +45,9 @@ class RetryTest {
     Retry.HandleErrorIssue<Order> handleError = (o,e) -> { 
       return; 
     };
-    Retry<Order> r1 = new Retry<Order>(op, handleError, 3, 30000,
+    Retry<Order> r1 = new Retry<>(op, handleError, 3, 30000,
         e -> DatabaseUnavailableException.class.isAssignableFrom(e.getClass()));
-    Retry<Order> r2 = new Retry<Order>(op, handleError, 3, 30000,
+    Retry<Order> r2 = new Retry<>(op, handleError, 3, 30000,
         e -> DatabaseUnavailableException.class.isAssignableFrom(e.getClass()));
     User user = new User("Jim", "ABCD");
     Order order = new Order(user, "book", 10f);