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

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

visitor/src/test/java/com/iluwatar/visitor/CommanderTest.java

@@ -32,7 +32,7 @@ import static org.mockito.Mockito.verify;
  *
  * @author Jeroen Meulemeester
  */
-public class CommanderTest extends UnitTest<Commander> {
+class CommanderTest extends UnitTest<Commander> {
 
   /**
    * Create a new test instance for the given {@link Commander}.

visitor/src/test/java/com/iluwatar/visitor/CommanderVisitorTest.java

@@ -31,7 +31,7 @@ import java.util.Optional;
  *
  * @author Jeroen Meulemeester
  */
-public class CommanderVisitorTest extends VisitorTest<CommanderVisitor> {
+class CommanderVisitorTest extends VisitorTest<CommanderVisitor> {
 
   /**
    * Create a new test instance for the given visitor.

visitor/src/test/java/com/iluwatar/visitor/SergeantTest.java

@@ -32,7 +32,7 @@ import static org.mockito.Mockito.verify;
  *
  * @author Jeroen Meulemeester
  */
-public class SergeantTest extends UnitTest<Sergeant> {
+class SergeantTest extends UnitTest<Sergeant> {
 
   /**
    * Create a new test instance for the given {@link Sergeant}.

visitor/src/test/java/com/iluwatar/visitor/SergeantVisitorTest.java

@@ -31,7 +31,7 @@ import java.util.Optional;
  *
  * @author Jeroen Meulemeester
  */
-public class SergeantVisitorTest extends VisitorTest<SergeantVisitor> {
+class SergeantVisitorTest extends VisitorTest<SergeantVisitor> {
 
   /**
    * Create a new test instance for the given visitor.

visitor/src/test/java/com/iluwatar/visitor/SoldierTest.java

@@ -32,7 +32,7 @@ import static org.mockito.Mockito.verify;
  *
  * @author Jeroen Meulemeester
  */
-public class SoldierTest extends UnitTest<Soldier> {
+class SoldierTest extends UnitTest<Soldier> {
 
   /**
    * Create a new test instance for the given {@link Soldier}.

visitor/src/test/java/com/iluwatar/visitor/SoldierVisitorTest.java

@@ -31,7 +31,7 @@ import java.util.Optional;
  *
  * @author Jeroen Meulemeester
  */
-public class SoldierVisitorTest extends VisitorTest<SoldierVisitor> {
+class SoldierVisitorTest extends VisitorTest<SoldierVisitor> {
 
   /**
    * Create a new test instance for the given visitor.

visitor/src/test/java/com/iluwatar/visitor/VisitorTest.java

@@ -48,12 +48,12 @@ public abstract class VisitorTest<V extends UnitVisitor> {
   private InMemoryAppender appender;
 
   @BeforeEach
-  public void setUp() {
+  void setUp() {
     appender = new InMemoryAppender();
   }
 
   @AfterEach
-  public void tearDown() {
+  void tearDown() {
     appender.stop();
   }