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

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

strategy/src/test/java/com/iluwatar/strategy/DragonSlayerTest.java

@@ -35,7 +35,7 @@ import org.junit.jupiter.api.Test;
  *
  * @author Jeroen Meulemeester
  */
-public class DragonSlayerTest {
+class DragonSlayerTest {
 
   /**
    * Verify if the dragon slayer uses the strategy during battle.

strategy/src/test/java/com/iluwatar/strategy/DragonSlayingStrategyTest.java

@@ -43,7 +43,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Jeroen Meulemeester
  */
-public class DragonSlayingStrategyTest {
+class DragonSlayingStrategyTest {
 
   /**
    * Assembles test parameters.
@@ -70,12 +70,12 @@ public class DragonSlayingStrategyTest {
   private InMemoryAppender appender;
 
   @BeforeEach
-  public void setUp() {
+  void setUp() {
     appender = new InMemoryAppender();
   }
 
   @AfterEach
-  public void tearDown() {
+  void tearDown() {
     appender.stop();
   }
 
@@ -85,7 +85,7 @@ public class DragonSlayingStrategyTest {
    */
   @ParameterizedTest
   @MethodSource("dataProvider")
-  public void testExecute(DragonSlayingStrategy strategy, String expectedResult) {
+  void testExecute(DragonSlayingStrategy strategy, String expectedResult) {
     strategy.execute();
     assertEquals(expectedResult, appender.getLastMessage());
     assertEquals(1, appender.getLogSize());