Fix sonar issues

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

@@ -85,13 +85,14 @@ public class App {
         // installed and socket connection is open).
         App app = new App(isDbMongo(args));
         app.useReadAndWriteThroughStrategy();
-        System.out.println("==============================================");
+        String splitLine = "==============================================";
+        LOGGER.info(splitLine);
         app.useReadThroughAndWriteAroundStrategy();
-        System.out.println("==============================================");
+        LOGGER.info(splitLine);
         app.useReadThroughAndWriteBehindStrategy();
-        System.out.println("==============================================");
+        LOGGER.info(splitLine);
         app.useCacheAsideStategy();
-        System.out.println("==============================================");
+        LOGGER.info(splitLine);
     }
 
     /**

caching/src/main/java/com/iluwatar/caching/AppManager.java

@@ -26,6 +26,7 @@ package com.iluwatar.caching;
 import java.util.Optional;
 
 import com.iluwatar.caching.database.DbManager;
+import lombok.Data;
 import lombok.extern.slf4j.Slf4j;
 
 /**
@@ -37,11 +38,12 @@ import lombok.extern.slf4j.Slf4j;
  * appropriate function in the CacheStore class.
  */
 @Slf4j
+@Data
 public class AppManager {
   /**
    * Caching Policy.
    */
-  private static CachingPolicy cachingPolicy;
+  private CachingPolicy cachingPolicy;
   /**
    * Database Manager.
    */

caching/src/main/java/com/iluwatar/caching/CacheStore.java

@@ -43,11 +43,11 @@ public class CacheStore {
   /**
    * Lru cache see {@link LruCache}.
    */
-  private static LruCache cache;
+  private LruCache cache;
   /**
    * DbManager.
    */
-  private DbManager dbManager;
+  private final DbManager dbManager;
 
   /**
    * Cache Store.

caching/src/main/java/com/iluwatar/caching/database/MongoDb.java

@@ -45,7 +45,7 @@ public class MongoDb implements DbManager {
         var iterable = db
                 .getCollection(CachingConstants.USER_ACCOUNT)
                 .find(new Document(USER_ID, userId));
-        if (iterable == null) {
+        if (iterable.first()==null) {
             return null;
         }
         Document doc = iterable.first();

caching/src/main/java/com/iluwatar/caching/database/VirtualDb.java

@@ -13,14 +13,14 @@ public class VirtualDb implements DbManager {
     /**
      * Virtual DataBase.
      */
-    private Map<String, UserAccount> virtualDB;
+    private Map<String, UserAccount> db;
 
     /**
      * Creates new HashMap.
      */
     @Override
     public void connect() {
-        virtualDB = new HashMap<>();
+        db = new HashMap<>();
     }
 
     /**
@@ -30,8 +30,8 @@ public class VirtualDb implements DbManager {
      */
     @Override
     public UserAccount readFromDb(final String userId) {
-        if (virtualDB.containsKey(userId)) {
-            return virtualDB.get(userId);
+        if (db.containsKey(userId)) {
+            return db.get(userId);
         }
         return null;
     }
@@ -43,7 +43,7 @@ public class VirtualDb implements DbManager {
      */
     @Override
     public UserAccount writeToDb(final UserAccount userAccount) {
-        virtualDB.put(userAccount.getUserId(), userAccount);
+        db.put(userAccount.getUserId(), userAccount);
         return userAccount;
     }
 
@@ -54,8 +54,7 @@ public class VirtualDb implements DbManager {
      */
     @Override
     public UserAccount updateDb(final UserAccount userAccount) {
-        virtualDB.put(userAccount.getUserId(), userAccount);
-        return userAccount;
+        return writeToDb(userAccount);
     }
 
     /**