squid:S2974 - Classes without public constructors should be final

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

@@ -33,7 +33,7 @@ import java.text.ParseException;
  * CacheStore class.
  *
  */
-public class AppManager {
+public final class AppManager {
 
   private static CachingPolicy cachingPolicy;
 

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

@@ -43,7 +43,7 @@ import com.mongodb.client.model.UpdateOptions;
  * during runtime (createVirtualDB()).</p>
  * 
  */
-public class DbManager {
+public final class DbManager {
 
   private static MongoClient mongoClient;
   private static MongoDatabase db;