docs: update unit of work

unit-of-work/src/main/java/com/iluwatar/unitofwork/App.java

@@ -44,7 +44,7 @@ public class App {
     var silverTrident = new Weapon(3, "silver trident");
 
     // create repository
-    var weaponRepository = new ArmsDealer(new HashMap<String, List<Weapon>>(),
+    var weaponRepository = new ArmsDealer(new HashMap<>(),
             new WeaponDatabase());
 
     // perform operations on the weapons

unit-of-work/src/main/java/com/iluwatar/unitofwork/ArmsDealer.java

@@ -73,7 +73,7 @@ public class ArmsDealer implements UnitOfWork<Weapon> {
    */
   @Override
   public void commit() {
-    if (context == null || context.size() == 0) {
+    if (context == null || context.isEmpty()) {
       return;
     }
     LOGGER.info("Commit started");