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

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

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/FilterManagerTest.java

@@ -39,7 +39,7 @@ import org.junit.jupiter.api.Test;
  *
  * @author Jeroen Meulemeester
  */
-public class FilterManagerTest {
+class FilterManagerTest {
 
   @Test
   void testFilterRequest() {

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/FilterTest.java

@@ -38,7 +38,7 @@ import org.junit.jupiter.params.provider.MethodSource;
  *
  * @author Jeroen Meulemeester
  */
-public class FilterTest {
+class FilterTest {
 
   private static final Order PERFECT_ORDER =
       new Order("name", "12345678901", "addr", "dep", "order");
@@ -89,7 +89,7 @@ public class FilterTest {
 
   @ParameterizedTest
   @MethodSource("getTestData")
-  public void testExecute(Filter filter, Order order, String expectedResult) {
+  void testExecute(Filter filter, Order order, String expectedResult) {
     final var result = filter.execute(order);
     assertNotNull(result);
     assertEquals(expectedResult, result.trim());
@@ -97,7 +97,7 @@ public class FilterTest {
 
   @ParameterizedTest
   @MethodSource("getTestData")
-  public void testNext(Filter filter) {
+  void testNext(Filter filter) {
     assertNull(filter.getNext());
     assertSame(filter, filter.getLast());
   }

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/OrderTest.java

@@ -33,7 +33,7 @@ import org.junit.jupiter.api.Test;
  *
  * @author Jeroen Meulemeester
  */
-public class OrderTest {
+class OrderTest {
 
   private static final String EXPECTED_VALUE = "test";