Addressing review comments, Deleting unintentional file and used FAILURE constant in ClientTest as well

Fix redundant list alloc in LotteryNumbers

README.md

@@ -8,7 +8,6 @@
 [![License MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/LICENSE.md)
 [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Quality Gate](https://sonarcloud.io/api/project_badges/measure?project=com.iluwatar%3Ajava-design-patterns&metric=alert_status)](https://sonarcloud.io/dashboard/index/com.iluwatar%3Ajava-design-patterns)
-[![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/1503/badge)](https://bestpractices.coreinfrastructure.org/projects/1503)
 
 # Introduction
 

abstract-document/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>abstract-document</artifactId>
     <dependencies>

abstract-factory/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>abstract-factory</artifactId>
   <dependencies>

acyclic-visitor/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	
 	<artifactId>acyclic-visitor</artifactId>

adapter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>adapter</artifactId>
   <dependencies>

aggregator-microservices/aggregator-service/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/information-microservice/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/inventory-microservice/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
     <artifactId>aggregator-microservices</artifactId>

ambassador/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>ambassador</artifactId>

ambassador/src/main/java/com/iluwatar/ambassador/RemoteService.java

@@ -22,6 +22,7 @@
  */
 package com.iluwatar.ambassador;
 
+import com.iluwatar.ambassador.util.RandomProvider;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -31,9 +32,10 @@ import static java.lang.Thread.sleep;
  * A remote legacy application represented by a Singleton implementation.
  */
 public class RemoteService implements RemoteServiceInterface {
-
+  static final int THRESHOLD = 200;
   private static final Logger LOGGER = LoggerFactory.getLogger(RemoteService.class);
   private static RemoteService service = null;
+  private final RandomProvider randomProvider;
 
   static synchronized RemoteService getRemoteService() {
     if (service == null) {
@@ -42,24 +44,33 @@ public class RemoteService implements RemoteServiceInterface {
     return service;
   }
 
-  private RemoteService() {}
+  private RemoteService() {
+    this(Math::random);
+  }
 
+  /**
+   * This constuctor is used for testing purposes only.
+   */
+  RemoteService(RandomProvider randomProvider) {
+    this.randomProvider = randomProvider;
+  }
   /**
    * Remote function takes a value and multiplies it by 10 taking a random amount of time.
    * Will sometimes return -1. This imitates connectivity issues a client might have to account for.
    * @param value integer value to be multiplied.
-   * @return if waitTime is more than 200ms, it returns value * 10, otherwise -1.
+   * @return if waitTime is less than {@link RemoteService#THRESHOLD}, it returns value * 10,
+   *     otherwise {@link RemoteServiceInterface#FAILURE}.
    */
   @Override
   public long doRemoteFunction(int value) {
 
-    long waitTime = (long) Math.floor(Math.random() * 1000);
+    long waitTime = (long) Math.floor(randomProvider.random() * 1000);
 
     try {
       sleep(waitTime);
     } catch (InterruptedException e) {
       LOGGER.error("Thread sleep state interrupted", e);
     }
-    return waitTime >= 200 ? value * 10 : -1;
+    return waitTime <= THRESHOLD ? value * 10 : FAILURE;
   }
 }

ambassador/src/main/java/com/iluwatar/ambassador/RemoteServiceInterface.java

@@ -26,6 +26,7 @@ package com.iluwatar.ambassador;
  * Interface shared by ({@link RemoteService}) and ({@link ServiceAmbassador}).
  */
 interface RemoteServiceInterface {
+  int FAILURE = -1;
 
   long doRemoteFunction(int value) throws Exception;
 }

ambassador/src/main/java/com/iluwatar/ambassador/ServiceAmbassador.java

@@ -59,15 +59,15 @@ public class ServiceAmbassador implements RemoteServiceInterface {
   private long safeCall(int value) {
 
     int retries = 0;
-    long result = -1;
+    long result = FAILURE;
 
     for (int i = 0; i < RETRIES; i++) {
 
       if (retries >= RETRIES) {
-        return -1;
+        return FAILURE;
       }
 
-      if ((result = checkLatency(value)) == -1) {
+      if ((result = checkLatency(value)) == FAILURE) {
         LOGGER.info("Failed to reach remote: (" + (i + 1) + ")");
         retries++;
         try {

ambassador/src/main/java/com/iluwatar/ambassador/util/RandomProvider.java

@@ -0,0 +1,8 @@
+package com.iluwatar.ambassador.util;
+
+/**
+ * An interface for randomness. Useful for testing purposes.
+ */
+public interface RandomProvider {
+  double random();
+}

ambassador/src/test/java/com/iluwatar/ambassador/ClientTest.java

@@ -24,6 +24,8 @@ package com.iluwatar.ambassador;
 
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 /**
  * Test for {@link Client}
  */
@@ -35,6 +37,6 @@ public class ClientTest {
     Client client = new Client();
     long result = client.useService(10);
 
-    assert result == 100 || result == -1;
+    assertTrue(result == 100 || result == RemoteService.FAILURE);
   }
 }

ambassador/src/test/java/com/iluwatar/ambassador/RemoteServiceTest.java

@@ -22,16 +22,43 @@
  */
 package com.iluwatar.ambassador;
 
+import com.iluwatar.ambassador.util.RandomProvider;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 /**
  * Test for {@link RemoteService}
  */
 public class RemoteServiceTest {
 
   @Test
-  public void test() {
+  public void testFailedCall() {
-    long result = RemoteService.getRemoteService().doRemoteFunction(10);
+    RemoteService remoteService = new RemoteService(
-    assert result == 100 || result == -1;
+        new StaticRandomProvider(0.21));
+    long result = remoteService.doRemoteFunction(10);
+    assertEquals(RemoteServiceInterface.FAILURE, result);
+  }
+
+  @Test
+  public void testSuccessfulCall() {
+    RemoteService remoteService = new RemoteService(
+        new StaticRandomProvider(0.2));
+    long result = remoteService.doRemoteFunction(10);
+    assertEquals(100, result);
+  }
+
+  private class StaticRandomProvider implements RandomProvider {
+    private double value;
+
+    StaticRandomProvider(double value) {
+      this.value = value;
+    }
+
+    @Override
+    public double random() {
+      return value;
+    }
   }
 }

ambassador/src/test/java/com/iluwatar/ambassador/ServiceAmbassadorTest.java

@@ -24,6 +24,8 @@ package com.iluwatar.ambassador;
 
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 /**
  * Test for {@link ServiceAmbassador}
  */
@@ -32,6 +34,6 @@ public class ServiceAmbassadorTest {
   @Test
   public void test() {
     long result = new ServiceAmbassador().doRemoteFunction(10);
-    assert result == 100 || result == -1;
+    assertTrue(result == 100 || result == RemoteServiceInterface.FAILURE);
   }
 }

api-gateway/api-gateway-service/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway-service</artifactId>

api-gateway/image-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
 
   <modelVersion>4.0.0</modelVersion>

api-gateway/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway</artifactId>

api-gateway/price-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
 
   <modelVersion>4.0.0</modelVersion>

async-method-invocation/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>async-method-invocation</artifactId>
   <dependencies>

balking/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

bridge/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>bridge</artifactId>
   <dependencies>

builder/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>builder</artifactId>
   <dependencies>

business-delegate/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>business-delegate</artifactId>
 	<dependencies>

caching/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>caching</artifactId>
   <dependencies>

callback/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>callback</artifactId>
   <dependencies>

chain/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>chain</artifactId>
   <dependencies>

collection-pipeline/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>collection-pipeline</artifactId>
   <dependencies>

command/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>command</artifactId>
   <dependencies>

composite/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>composite</artifactId>
   <dependencies>

converter/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
     <dependencies>

cqrs/pom.xml

@@ -21,7 +21,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>cqrs</artifactId>
 	<dependencies>

dao/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>dao</artifactId>
 

data-bus/pom.xml

@@ -33,7 +33,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>data-bus</artifactId>
     <dependencies>

data-mapper/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>data-mapper</artifactId>
 	<dependencies>

data-transfer-object/pom.xml

@@ -28,7 +28,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>data-transfer-object</artifactId>
     <dependencies>

decorator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>decorator</artifactId>
   <dependencies>

delegation/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

dependency-injection/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>dependency-injection</artifactId>
   <dependencies>

dirty-flag/pom.xml

@@ -29,11 +29,11 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <groupId>com.iluwatar</groupId>
   <artifactId>dirty-flag</artifactId>
-  <version>1.20.0-SNAPSHOT</version>
+  <version>1.21.0-SNAPSHOT</version>
   <name>dirty-flag</name>
   <url>http://maven.apache.org</url>
   <properties>

double-checked-locking/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-checked-locking</artifactId>
   <dependencies>

double-dispatch/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-dispatch</artifactId>
   <dependencies>

eip-aggregator/pom.xml

@@ -26,7 +26,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

eip-message-channel/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-message-channel</artifactId>
 	<dependencies>

eip-publish-subscribe/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-publish-subscribe</artifactId>
 	<dependencies>

eip-splitter/pom.xml

@@ -26,7 +26,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

eip-wire-tap/pom.xml

@@ -26,7 +26,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

event-aggregator/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>event-aggregator</artifactId>
 	<dependencies>

event-asynchronous/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-asynchronous</artifactId>
   <dependencies>

event-driven-architecture/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>event-driven-architecture</artifactId>

event-queue/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-queue</artifactId>
   <dependencies>

event-sourcing/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-sourcing</artifactId>
   <dependencies>

execute-around/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>execute-around</artifactId>
   <dependencies>

extension-objects/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

facade/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>facade</artifactId>
   <dependencies>

factory-kit/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>factory-kit</artifactId>
     <dependencies>

factory-method/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>factory-method</artifactId>
   <dependencies>

feature-toggle/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

fluentinterface/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

flux/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>flux</artifactId>
   <dependencies>

flyweight/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>flyweight</artifactId>
   <dependencies>

front-controller/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>front-controller</artifactId>
 	<dependencies>

guarded-suspension/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <packaging>jar</packaging>
   <artifactId>guarded-suspension</artifactId>

half-sync-half-async/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>half-sync-half-async</artifactId>
   <dependencies>

hexagonal/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>hexagonal</artifactId>
   <dependencies>

hexagonal/src/main/java/com/iluwatar/hexagonal/domain/LotteryNumbers.java

@@ -22,13 +22,12 @@
  */
 package com.iluwatar.hexagonal.domain;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.List;
 import java.util.PrimitiveIterator;
 import java.util.Random;
 import java.util.Set;
+import java.util.Iterator;
 
 /**
  *
@@ -85,11 +84,10 @@ public class LotteryNumbers {
    * @return numbers as comma separated string
    */
   public String getNumbersAsString() {
-    List<Integer> list = new ArrayList<>();
-    list.addAll(numbers);
     StringBuilder builder = new StringBuilder();
+    Iterator<Integer> iterator = numbers.iterator();
     for (int i = 0; i < NUM_NUMBERS; i++) {
-      builder.append(list.get(i));
+      builder.append(iterator.next());
       if (i < NUM_NUMBERS - 1) {
         builder.append(",");
       }

intercepting-filter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>intercepting-filter</artifactId>
   <dependencies>

interpreter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>interpreter</artifactId>
   <dependencies>

iterator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>iterator</artifactId>
   <dependencies>

layers/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<groupId>com.iluwatar.layers</groupId>
 	<artifactId>layers</artifactId>

lazy-loading/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>lazy-loading</artifactId>
   <dependencies>

marker/pom.xml

@@ -24,7 +24,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

mediator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>mediator</artifactId>
   <dependencies>

memento/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>memento</artifactId>
   <dependencies>

model-view-controller/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>model-view-controller</artifactId>
   <dependencies>

model-view-presenter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>model-view-presenter</artifactId>
   <name>model-view-presenter</name>

module/.gitignore

@@ -0,0 +1,2 @@
+error.txt
+output.txt

module/error.txt

@@ -1,23 +0,0 @@
-====
-    The MIT License
-    Copyright (c) 2014 Ilkka Seppälä
-
-    Permission is hereby granted, free of charge, to any person obtaining a copy
-    of this software and associated documentation files (the "Software"), to deal
-    in the Software without restriction, including without limitation the rights
-    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-    copies of the Software, and to permit persons to whom the Software is
-    furnished to do so, subject to the following conditions:
-
-    The above copyright notice and this permission notice shall be included in
-    all copies or substantial portions of the Software.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-    THE SOFTWARE.
-====
-

module/output.txt

@@ -1,23 +0,0 @@
-====
-    The MIT License
-    Copyright (c) 2014 Ilkka Seppälä
-
-    Permission is hereby granted, free of charge, to any person obtaining a copy
-    of this software and associated documentation files (the "Software"), to deal
-    in the Software without restriction, including without limitation the rights
-    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-    copies of the Software, and to permit persons to whom the Software is
-    furnished to do so, subject to the following conditions:
-
-    The above copyright notice and this permission notice shall be included in
-    all copies or substantial portions of the Software.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-    THE SOFTWARE.
-====
-

module/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>module</artifactId>
 	<dependencies>

monad/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>monad</artifactId>
     <dependencies>

monostate/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>monostate</artifactId>
   <dependencies>

multiton/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>multiton</artifactId>
   <dependencies>

mute-idiom/pom.xml

@@ -21,7 +21,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>mute-idiom</artifactId>
 	<dependencies>

mutex/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>mutex</artifactId>
   <dependencies>

naked-objects/dom/pom.xml

@@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>naked-objects-dom</artifactId>

naked-objects/fixture/pom.xml

@@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>naked-objects-fixture</artifactId>

naked-objects/integtests/pom.xml

@@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>naked-objects-integtests</artifactId>

naked-objects/pom.xml

@@ -15,7 +15,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>naked-objects</artifactId>
@@ -350,17 +350,17 @@
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-dom</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-fixture</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-webapp</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>
 
 		</dependencies>

naked-objects/webapp/pom.xml

@@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>naked-objects-webapp</artifactId>

null-object/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>null-object</artifactId>
   <dependencies>

object-mother/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>object-mother</artifactId>
     <dependencies>

object-pool/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>object-pool</artifactId>
   <dependencies>

observer/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>observer</artifactId>
   <dependencies>

page-object/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <artifactId>page-object</artifactId>
     <dependencies>

partial-response/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

poison-pill/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
   </parent>
   <artifactId>poison-pill</artifactId>
   <dependencies>

pom.xml

@@ -21,7 +21,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
     <packaging>pom</packaging>
     <inceptionYear>2014</inceptionYear>
     <properties>