Java 11 migration: patterns (remaining b-c) (#1081)

* Moves business-delegate pattern  to java 11

* Moves bytecode pattern  to java 11

* Moves caching pattern  to java 11

* Moves callback pattern  to java 11

* Moves chain pattern  to java 11

* Moves circuit-breaker pattern  to java 11

* Moves collection-pipeline pattern  to java 11

* Moves command pattern  to java 11

* Moves commander pattern  to java 11

* Moves composite pattern  to java 11

* Corrects test cases

callback/src/main/java/com/iluwatar/callback/App.java

@@ -43,8 +43,7 @@ public final class App {
    * Program entry point.
    */
   public static void main(final String[] args) {
-    Task task = new SimpleTask();
-    Callback callback = () -> LOGGER.info("I'm done now.");
-    task.executeWith(callback);
+    var task = new SimpleTask();
+    task.executeWith(() -> LOGGER.info("I'm done now."));
   }
 }

callback/src/main/java/com/iluwatar/callback/LambdasApp.java

@@ -42,8 +42,7 @@ public final class LambdasApp {
    * Program entry point.
    */
   public static void main(final String[] args) {
-    Task task = new SimpleTask();
-    Callback c = () -> LOGGER.info("I'm done now.");
-    task.executeWith(c);
+    var task = new SimpleTask();
+    task.executeWith(() -> LOGGER.info("I'm done now."));
   }
 }

callback/src/main/java/com/iluwatar/callback/Task.java

@@ -23,6 +23,8 @@
 
 package com.iluwatar.callback;
 
+import java.util.Optional;
+
 /**
  * Template-method class for callback hook execution.
  */
@@ -33,9 +35,7 @@ public abstract class Task {
    */
   final void executeWith(final Callback callback) {
     execute();
-    if (callback != null) {
-      callback.call();
-    }
+    Optional.ofNullable(callback).ifPresent(Callback::call);
   }
 
   public abstract void execute();

callback/src/test/java/com/iluwatar/callback/AppTest.java

@@ -25,15 +25,12 @@ package com.iluwatar.callback;
 
 import org.junit.jupiter.api.Test;
 
-import java.io.IOException;
-
 /**
  * Tests that Callback example runs without errors.
  */
 public class AppTest {
   @Test
-  public void test() throws IOException {
-    String[] args = {};
-    App.main(args);
+  public void test() {
+    App.main(new String[]{});
   }
 }

callback/src/test/java/com/iluwatar/callback/CallbackTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.callback;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Add a field as a counter. Every time the callback method is called increment this field. Unit
  * test checks that the field is being incremented.
- *
+ * <p>
  * Could be done with mock objects as well where the call method call is verified.
  */
 public class CallbackTest {
@@ -41,17 +41,17 @@ public class CallbackTest {
   public void test() {
     Callback callback = () -> callingCount++;
 
-    Task task = new SimpleTask();
+    var task = new SimpleTask();
 
-    assertEquals(new Integer(0), callingCount, "Initial calling count of 0");
+    assertEquals(Integer.valueOf(0), callingCount, "Initial calling count of 0");
 
     task.executeWith(callback);
 
-    assertEquals(new Integer(1), callingCount, "Callback called once");
+    assertEquals(Integer.valueOf(1), callingCount, "Callback called once");
 
     task.executeWith(callback);
 
-    assertEquals(new Integer(2), callingCount, "Callback called twice");
+    assertEquals(Integer.valueOf(2), callingCount, "Callback called twice");
 
   }
 }