dependencies: #2449 bump maven-checkstyle-plugin from 3.1.0 to 3.2.0 + resolve chec… (#2464)

* #2449 bump maven-checkstyle-plugin from 3.1.0 to 3.2.0 + resolve checkstyle issues

* remove FileSelectorJFrame.java to resolve checkstyle issue

* remove FileSelectorJFrame.java to resolve checkstyle issue

* remove FileSelectorJFrame.java to resolve checkstyle issue

* add refactored file with correct filename to resolve checkstyle issue

* add the test data

* change filenames from JFrame to Jframe for checkstyle

* fix code smell from  sonar report

* add new testcases to improve the test coverage

* remove code smell

special-case/src/main/java/com/iluwatar/specialcase/Db.java

@@ -27,6 +27,9 @@ package com.iluwatar.specialcase;
 import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * DB class for seeding user info.
+ */
 public class Db {
 
   private static Db instance;
@@ -113,6 +116,9 @@ public class Db {
     return itemName2Product.get(itemName);
   }
 
+  /**
+   * User class to store user info.
+   */
   public class User {
 
     private String userName;
@@ -130,6 +136,9 @@ public class Db {
     }
   }
 
+  /**
+   * Account info.
+   */
   public class Account {
 
     private Double amount;
@@ -156,6 +165,9 @@ public class Db {
     }
   }
 
+  /**
+   * Product info.
+   */
   public class Product {
 
     private Double price;