📍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>

subclass-sandbox/src/main/java/com/iluwatar/subclasssandbox/App.java

@@ -23,8 +23,7 @@
 
 package com.iluwatar.subclasssandbox;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import lombok.extern.slf4j.Slf4j;
 
 /**
  * The subclass sandbox pattern describes a basic idea, while not having a lot
@@ -33,10 +32,9 @@ import org.slf4j.LoggerFactory;
  * while all subclasses shouldn't have to be touched. So the base class has to be
  * able to provide all of the operations a derived class needs to perform.
  */
+@Slf4j
 public class App {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
-
   /**
    * Entry point of the main program.
    * @param args Program runtime arguments.