📍Use lombok, reformat, and optimize the code (#1560)

* Use lombok, reformat, and optimize the code

* Fix merge conflicts and some sonar issues

Co-authored-by: va1m <va1m@email.com>

lazy-loading/src/main/java/com/iluwatar/lazy/loading/App.java

@@ -23,8 +23,7 @@
 
 package com.iluwatar.lazy.loading;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * Lazy loading idiom defers object creation until needed.
@@ -34,10 +33,9 @@ import org.slf4j.LoggerFactory;
  * <p>Additional information and lazy loading flavours are described in
  * http://martinfowler.com/eaaCatalog/lazyLoad.html
  */
+@Slf4j
 public class App {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
-
   /**
    * Program entry point.
    *

lazy-loading/src/main/java/com/iluwatar/lazy/loading/Heavy.java

@@ -23,16 +23,14 @@
 
 package com.iluwatar.lazy.loading;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * Heavy objects are expensive to create.
  */
+@Slf4j
 public class Heavy {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Heavy.class);
-
   /**
    * Constructor.
    */

lazy-loading/src/main/java/com/iluwatar/lazy/loading/HolderNaive.java

@@ -23,16 +23,14 @@
 
 package com.iluwatar.lazy.loading;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * Simple implementation of the lazy loading idiom. However, this is not thread safe.
  */
+@Slf4j
 public class HolderNaive {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(HolderNaive.class);
-
   private Heavy heavy;
 
   /**

lazy-loading/src/main/java/com/iluwatar/lazy/loading/HolderThreadSafe.java

@@ -23,17 +23,15 @@
 
 package com.iluwatar.lazy.loading;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * Same as HolderNaive but with added synchronization. This implementation is thread safe, but each
  * {@link #getHeavy()} call costs additional synchronization overhead.
  */
+@Slf4j
 public class HolderThreadSafe {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(HolderThreadSafe.class);
-
   private Heavy heavy;
 
   /**

lazy-loading/src/main/java/com/iluwatar/lazy/loading/Java8Holder.java

@@ -24,17 +24,15 @@
 package com.iluwatar.lazy.loading;
 
 import java.util.function.Supplier;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * This lazy loader is thread safe and more efficient than {@link HolderThreadSafe}. It utilizes
  * Java 8 functional interface {@link Supplier} as {@link Heavy} factory.
  */
+@Slf4j
 public class Java8Holder {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Java8Holder.class);
-
   private Supplier<Heavy> heavy = this::createAndCacheHeavy;
 
   public Java8Holder() {

lazy-loading/src/test/java/com/iluwatar/lazy/loading/AbstractHolderTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.lazy.loading;
 
-import org.junit.jupiter.api.Test;
-
 import static java.time.Duration.ofMillis;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTimeout;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/19/15 - 11:58 AM
  *
@@ -56,7 +56,7 @@ public abstract class AbstractHolderTest {
    * This test shows that the heavy field is not instantiated until the method getHeavy is called
    */
   @Test
-  public void testGetHeavy() throws Exception {
+  void testGetHeavy() throws Exception {
     assertTimeout(ofMillis(3000), () -> {
       assertNull(getInternalHeavyValue());
       assertNotNull(getHeavy());

lazy-loading/src/test/java/com/iluwatar/lazy/loading/AppTest.java

@@ -28,7 +28,7 @@ import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
 /**
- * 
+ *
  * Application test
  *
  */