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

model-view-viewmodel/src/main/java/com/iluwatar/model/view/viewmodel/Book.java

@@ -27,6 +27,9 @@ package com.iluwatar.model.view.viewmodel;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 
+/**
+ * Book class.
+ */
 @AllArgsConstructor
 @Data
 public class Book {

model-view-viewmodel/src/main/java/com/iluwatar/model/view/viewmodel/BookService.java

@@ -27,6 +27,9 @@ package com.iluwatar.model.view.viewmodel;
 
 import java.util.List;
 
+/**
+ * Class representing a service to load books.
+ */
 public interface BookService {
   /* List all books
    * @return all books

model-view-viewmodel/src/main/java/com/iluwatar/model/view/viewmodel/BookServiceImpl.java

@@ -27,6 +27,9 @@ package com.iluwatar.model.view.viewmodel;
 import java.util.ArrayList;
 import java.util.List;
 
+/**
+ * Class that actually implement the books to load.
+ */
 public class BookServiceImpl implements BookService {
   private List<Book> designPatternBooks = new ArrayList<>();
 

model-view-viewmodel/src/main/java/com/iluwatar/model/view/viewmodel/BookViewModel.java

@@ -25,11 +25,13 @@
 package com.iluwatar.model.view.viewmodel;
 
 import java.util.List;
-
 import org.zkoss.bind.annotation.Command;
 import org.zkoss.bind.annotation.NotifyChange;
 import org.zkoss.zk.ui.select.annotation.WireVariable;
 
+/**
+ * BookViewModel class.
+ */
 public class BookViewModel {
   
   @WireVariable
@@ -56,7 +58,7 @@ public class BookViewModel {
    * and used to delete the selected book from the list of books. 
    */
   @Command
-  @NotifyChange({"selectedBook","bookList"})
+  @NotifyChange({"selectedBook", "bookList"})
   public void deleteBook() {
     if (selectedBook != null) {
       getBookList().remove(selectedBook);