refactor: remove code smell java:S5786 (#2159)

https://sonarcloud.io/organizations/iluwatar/rules?open=java%3AS5786&rule_key=java%3AS5786

model-view-presenter/src/test/java/com/iluwatar/model/view/presenter/FileLoaderTest.java

@@ -33,7 +33,7 @@ import org.junit.jupiter.api.Test;
  *
  * @author Jeroen Meulemeester
  */
-public class FileLoaderTest {
+class FileLoaderTest {
 
   @Test
   void testLoadData() {

model-view-presenter/src/test/java/com/iluwatar/model/view/presenter/FileSelectorPresenterTest.java

@@ -36,7 +36,7 @@ import org.junit.jupiter.api.Test;
  * This test case is responsible for testing our application by taking advantage of the
  * Model-View-Controller architectural pattern.
  */
-public class FileSelectorPresenterTest {
+class FileSelectorPresenterTest {
 
   /**
    * The Presenter component.
@@ -57,7 +57,7 @@ public class FileSelectorPresenterTest {
    * Initializes the components of the test case.
    */
   @BeforeEach
-  public void setUp() {
+  void setUp() {
     this.stub = new FileSelectorStub();
     this.loader = new FileLoader();
     presenter = new FileSelectorPresenter(this.stub);