diff --git a/patterns-modules/design-patterns-behavioral-2/src/main/java/com/baeldung/nullconversion/Delivery.java b/patterns-modules/design-patterns-behavioral-2/src/main/java/com/baeldung/nullconversion/Delivery.java
index 3c584d9566..7f18cfd9bc 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/main/java/com/baeldung/nullconversion/Delivery.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/main/java/com/baeldung/nullconversion/Delivery.java
@@ -32,4 +32,7 @@ public class Delivery {
     public static Delivery freeDelivery() {
         return new Delivery("Free delivery");
     }
+    public static Delivery defaultDelivery() {
+        return new Delivery("Default delivery");
+    }
 }
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/OnePersonDeliveryServiceUnitTest.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/OnePersonDeliveryServiceUnitTest.java
index 01cd658bd1..304458b213 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/OnePersonDeliveryServiceUnitTest.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/OnePersonDeliveryServiceUnitTest.java
@@ -7,6 +7,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import com.baeldung.nullconversion.service.OnePersonExplicitDeliveryService;
 import com.baeldung.nullconversion.service.OnePersonGuavaOptionalDeliveryService;
 import com.baeldung.nullconversion.service.OnePersonOptionalDeliveryService;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ArgumentsSource;
 
@@ -27,13 +28,4 @@ class OnePersonDeliveryServiceUnitTest {
         Delivery actual = deliveryService.calculateDeliveryForPerson(1L);
         assertThat(actual).isEqualTo(expected);
     }
-
-    @ParameterizedTest
-    @ArgumentsSource(NullReturningPersonChainProvider.class)
-    void givenMockDeliverServiceWhenNullValuesThenGuavaOptionalServiceThrowsException(Person person) {
-        DeliveryService deliveryService = new OnePersonGuavaOptionalDeliveryService(person);
-        assertThatExceptionOfType(NullPointerException.class)
-          .isThrownBy(() -> deliveryService.calculateDeliveryForPerson(1L));
-
-    }
 }
\ No newline at end of file
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/PersonProvider.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/PersonProvider.java
index d31d9d8ec4..301e859fe7 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/PersonProvider.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/PersonProvider.java
@@ -18,10 +18,10 @@ public class PersonProvider implements ArgumentsProvider {
 
         return Stream.of(
           Arguments.of(person, Delivery.freeDelivery()),
-          Arguments.of(cloneAndMutate(person, p -> p.getAddress().getZipCode().setCode("")), null),
-          Arguments.of(cloneAndMutate(person, p -> p.getAddress().setZipCode(null)), null),
-          Arguments.of(cloneAndMutate(person, p -> p.setAddress(null)), null),
-          Arguments.of(null, null)
+          Arguments.of(cloneAndMutate(person, p -> p.getAddress().getZipCode().setCode("")), Delivery.defaultDelivery()),
+          Arguments.of(cloneAndMutate(person, p -> p.getAddress().setZipCode(null)), Delivery.defaultDelivery()),
+          Arguments.of(cloneAndMutate(person, p -> p.setAddress(null)), Delivery.defaultDelivery()),
+          Arguments.of(null, Delivery.defaultDelivery())
         );
 
     }
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/MockOnePersonDeliveryServiceBase.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/MockOnePersonDeliveryServiceBase.java
index 973f8bce97..1080f69d97 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/MockOnePersonDeliveryServiceBase.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/MockOnePersonDeliveryServiceBase.java
@@ -23,7 +23,7 @@ public abstract class MockOnePersonDeliveryServiceBase implements DeliveryServic
             String code = zipCode.getCode();
             return calculateDeliveryForZipCode(code);
         }
-        return null;
+        return Delivery.defaultDelivery();
     }
 
     public Delivery calculateDeliveryForPersonWithOptional(Long id) {
@@ -32,7 +32,7 @@ public abstract class MockOnePersonDeliveryServiceBase implements DeliveryServic
           .map(Address::getZipCode)
           .map(ZipCode::getCode)
           .map(this::calculateDeliveryForZipCode)
-          .orElse(null);
+          .orElse(Delivery.defaultDelivery());
     }
 
     protected Person getPersonById(Long id) {
@@ -41,7 +41,7 @@ public abstract class MockOnePersonDeliveryServiceBase implements DeliveryServic
 
     protected Delivery calculateDeliveryForZipCode(String zipCode) {
         if (zipCode == null || zipCode.isEmpty()) {
-            return null;
+            return Delivery.defaultDelivery();
         } else {
             return Delivery.freeDelivery();
         }
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonExplicitDeliveryService.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonExplicitDeliveryService.java
index 652d0a002b..7d81d3cf51 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonExplicitDeliveryService.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonExplicitDeliveryService.java
@@ -19,6 +19,6 @@ public class OnePersonExplicitDeliveryService extends MockOnePersonDeliveryServi
             String code = zipCode.getCode();
             return calculateDeliveryForZipCode(code);
         }
-        return null;
+        return Delivery.defaultDelivery();
     }
 }
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonGuavaOptionalDeliveryService.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonGuavaOptionalDeliveryService.java
index 29d42789a0..f495576e87 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonGuavaOptionalDeliveryService.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonGuavaOptionalDeliveryService.java
@@ -20,7 +20,7 @@ public class OnePersonGuavaOptionalDeliveryService extends MockOnePersonDelivery
           .transform(Address::getZipCode)
           .transform(ZipCode::getCode)
           .transform(this::calculateDeliveryForZipCode)
-          .orNull();
+          .or(Delivery.defaultDelivery());
     }
 
 }
diff --git a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonOptionalDeliveryService.java b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonOptionalDeliveryService.java
index 586f0009ea..1a7ab5d870 100644
--- a/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonOptionalDeliveryService.java
+++ b/patterns-modules/design-patterns-behavioral-2/src/test/java/com/baeldung/nullconversion/service/OnePersonOptionalDeliveryService.java
@@ -20,7 +20,7 @@ public class OnePersonOptionalDeliveryService extends MockOnePersonDeliveryServi
           .map(Address::getZipCode)
           .map(ZipCode::getCode)
           .map(this::calculateDeliveryForZipCode)
-          .orElse(null);
+          .orElse(Delivery.defaultDelivery());
     }
 
 }