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

object-pool/src/test/java/com/iluwatar/object/pool/OliphauntPoolTest.java

@@ -25,15 +25,10 @@ package com.iluwatar.object.pool;
 
 import org.junit.jupiter.api.Test;
 
-import java.util.Arrays;
 import java.util.List;
 
 import static java.time.Duration.ofMillis;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotSame;
-import static org.junit.jupiter.api.Assertions.assertSame;
-import static org.junit.jupiter.api.Assertions.assertTimeout;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.*;
 
 /**
  * Date: 12/27/15 - 1:05 AM
@@ -115,7 +110,7 @@ public class OliphauntPoolTest {
 
       // The order of the returned instances is not determined, so just put them in a list
       // and verify if both expected instances are in there.
-      final List<Oliphaunt> oliphaunts = Arrays.asList(pool.checkOut(), pool.checkOut());
+      final List<Oliphaunt> oliphaunts = List.of(pool.checkOut(), pool.checkOut());
       assertEquals(pool.toString(), "Pool available=0 inUse=2");
       assertTrue(oliphaunts.contains(firstOliphaunt));
       assertTrue(oliphaunts.contains(secondOliphaunt));