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-presenter/etc/model-view-presenter.urm.puml

@@ -16,7 +16,7 @@ package com.iluwatar.model.view.presenter {
     + loadData() : String
     + setFileName(fileName : String)
   }
-  class FileSelectorJFrame {
+  class FileSelectorJframe {
     - area : JTextArea
     - cancel : JButton
     - contents : JLabel
@@ -27,7 +27,7 @@ package com.iluwatar.model.view.presenter {
     - panel : JPanel
     - presenter : FileSelectorPresenter
     - serialVersionUID : long {static}
-    + FileSelectorJFrame()
+    + FileSelectorJframe()
     + actionPerformed(e : ActionEvent)
     + close()
     + displayData(data : String)
@@ -81,10 +81,10 @@ package com.iluwatar.model.view.presenter {
     + showMessage(String) {abstract}
   }
 }
-FileSelectorJFrame -->  "-presenter" FileSelectorPresenter
+FileSelectorJframe -->  "-presenter" FileSelectorPresenter
 FileSelectorStub -->  "-presenter" FileSelectorPresenter
 FileSelectorPresenter -->  "-view" FileSelectorView
 FileSelectorPresenter -->  "-loader" FileLoader
-FileSelectorJFrame ..|> FileSelectorView 
+FileSelectorJframe ..|> FileSelectorView 
 FileSelectorStub ..|> FileSelectorView 
 @enduml