diff --git a/mapstruct-3/src/main/java/com/baeldung/dto/AncestorDto.java b/mapstruct-3/src/main/java/com/baeldung/dto/AncestorDto.java
new file mode 100644
index 000000000000..48b489faa08d
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/dto/AncestorDto.java
@@ -0,0 +1,43 @@
+package com.baeldung.dto;
+
+public class AncestorDto {
+
+    private String firstName;
+
+    private Double weight;
+
+    private String vatNumber;
+
+    public AncestorDto() {
+    }
+
+    public AncestorDto(String firstName, Double weight, String vatNumber) {
+        this.firstName = firstName;
+        this.weight = weight;
+        this.vatNumber = vatNumber;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public Double getWeight() {
+        return weight;
+    }
+
+    public void setWeight(Double weight) {
+        this.weight = weight;
+    }
+
+    public String getVatNumber() {
+        return vatNumber;
+    }
+
+    public void setVatNumber(String vatNumber) {
+        this.vatNumber = vatNumber;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/dto/OrderDto.java b/mapstruct-3/src/main/java/com/baeldung/dto/OrderDto.java
new file mode 100644
index 000000000000..4b5277aa78bd
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/dto/OrderDto.java
@@ -0,0 +1,45 @@
+package com.baeldung.dto;
+
+import java.util.List;
+
+public class OrderDto {
+
+    private String transactionId;
+
+    private List<String> orderItemIds;
+
+    private PaymentDto paymentDto;
+
+    public OrderDto(String transactionId, List<String> orderItemIds, PaymentDto paymentDto) {
+        this.transactionId = transactionId;
+        this.orderItemIds = orderItemIds;
+        this.paymentDto = paymentDto;
+    }
+
+    public OrderDto() {
+    }
+
+    public String getTransactionId() {
+        return transactionId;
+    }
+
+    public void setTransactionId(String transactionId) {
+        this.transactionId = transactionId;
+    }
+
+    public List<String> getOrderItemIds() {
+        return orderItemIds;
+    }
+
+    public void setOrderItemIds(List<String> orderItemIds) {
+        this.orderItemIds = orderItemIds;
+    }
+
+    public PaymentDto getPaymentDto() {
+        return paymentDto;
+    }
+
+    public void setPaymentDto(PaymentDto paymentDto) {
+        this.paymentDto = paymentDto;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/dto/PaymentDto.java b/mapstruct-3/src/main/java/com/baeldung/dto/PaymentDto.java
new file mode 100644
index 000000000000..94768c008ab7
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/dto/PaymentDto.java
@@ -0,0 +1,21 @@
+package com.baeldung.dto;
+
+public class PaymentDto {
+
+    private String type;
+
+    public PaymentDto() {
+    }
+
+    public PaymentDto(String type) {
+        this.type = type;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/entity/GrandDad.java b/mapstruct-3/src/main/java/com/baeldung/entity/GrandDad.java
new file mode 100644
index 000000000000..6b9fabae0d1b
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/entity/GrandDad.java
@@ -0,0 +1,43 @@
+package com.baeldung.entity;
+
+public class GrandDad {
+
+    private Identity identity;
+
+    private String weight;
+
+    private String vatNumber;
+
+    public GrandDad() {
+    }
+
+    public GrandDad(Identity identity, String weight, String vatNumber) {
+        this.identity = identity;
+        this.weight = weight;
+        this.vatNumber = vatNumber;
+    }
+
+    public Identity getIdentity() {
+        return identity;
+    }
+
+    public void setIdentity(Identity identity) {
+        this.identity = identity;
+    }
+
+    public String getWeight() {
+        return weight;
+    }
+
+    public void setWeight(String weight) {
+        this.weight = weight;
+    }
+
+    public String getVatNumber() {
+        return vatNumber;
+    }
+
+    public void setVatNumber(String vatNumber) {
+        this.vatNumber = vatNumber;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/entity/Identity.java b/mapstruct-3/src/main/java/com/baeldung/entity/Identity.java
new file mode 100644
index 000000000000..814cd7b472e2
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/entity/Identity.java
@@ -0,0 +1,32 @@
+package com.baeldung.entity;
+
+public class Identity {
+
+    private String name;
+    private String surname;
+
+    public Identity() {
+    }
+
+    public Identity(String name, String surname) {
+        this.name = name;
+        this.surname = surname;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getSurname() {
+        return surname;
+    }
+
+    public void setSurname(String surname) {
+        this.surname = surname;
+    }
+
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/entity/Order.java b/mapstruct-3/src/main/java/com/baeldung/entity/Order.java
new file mode 100644
index 000000000000..f757e5a8b11c
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/entity/Order.java
@@ -0,0 +1,45 @@
+package com.baeldung.entity;
+
+import java.util.List;
+
+public class Order {
+
+    private String transactionId;
+
+    private List<String> orderItemIds;
+
+    private Payment payment;
+
+    public Order(String transactionId, List<String> orderItemIds, Payment payment) {
+        this.transactionId = transactionId;
+        this.orderItemIds = orderItemIds;
+        this.payment = payment;
+    }
+
+    public Order() {
+    }
+
+    public String getTransactionId() {
+        return transactionId;
+    }
+
+    public void setTransactionId(String transactionId) {
+        this.transactionId = transactionId;
+    }
+
+    public List<String> getOrderItemIds() {
+        return orderItemIds;
+    }
+
+    public void setOrderItemIds(List<String> orderItemIds) {
+        this.orderItemIds = orderItemIds;
+    }
+
+    public Payment getPayment() {
+        return payment;
+    }
+
+    public void setPayment(Payment payment) {
+        this.payment = payment;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/entity/Payment.java b/mapstruct-3/src/main/java/com/baeldung/entity/Payment.java
new file mode 100644
index 000000000000..426f2f4991ec
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/entity/Payment.java
@@ -0,0 +1,21 @@
+package com.baeldung.entity;
+
+public class Payment {
+
+    private String type;
+
+    public Payment() {
+    }
+
+    public Payment(String type) {
+        this.type = type;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/mapper/AncestorMapper.java b/mapstruct-3/src/main/java/com/baeldung/mapper/AncestorMapper.java
new file mode 100644
index 000000000000..5236a7c7f560
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/mapper/AncestorMapper.java
@@ -0,0 +1,15 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.AncestorDto;
+import com.baeldung.entity.GrandDad;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+
+@Mapper
+public interface AncestorMapper {
+
+    @Mapping(source = "identity.name", target = "firstName")
+    @Mapping(source = "weight", target = "weight", numberFormat = "###.#")
+    AncestorDto toDto(GrandDad grandDad);
+
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/mapper/MediaMapper.java b/mapstruct-3/src/main/java/com/baeldung/mapper/MediaMapper.java
index 2629a1820a3e..e240b121e8d3 100644
--- a/mapstruct-3/src/main/java/com/baeldung/mapper/MediaMapper.java
+++ b/mapstruct-3/src/main/java/com/baeldung/mapper/MediaMapper.java
@@ -1,9 +1,8 @@
 package com.baeldung.mapper;
 
-import org.mapstruct.Mapper;
-
 import com.baeldung.dto.MediaDto;
 import com.baeldung.entity.Media;
+import org.mapstruct.Mapper;
 
 @Mapper
 public interface MediaMapper {
diff --git a/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithAfterMapping.java b/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithAfterMapping.java
new file mode 100644
index 000000000000..efc4749ee90b
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithAfterMapping.java
@@ -0,0 +1,29 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.OrderDto;
+import com.baeldung.entity.Order;
+import org.mapstruct.AfterMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.MappingTarget;
+
+import java.util.ArrayList;
+
+@Mapper(uses = PaymentMapper.class)
+public interface OrderMapperWithAfterMapping {
+
+    @Mapping(source = "payment", target = "paymentDto")
+    OrderDto toDto(Order order);
+
+    @AfterMapping
+    default OrderDto postProcessing(@MappingTarget OrderDto orderDto) {
+        if (orderDto.getOrderItemIds() == null) {
+            orderDto.setOrderItemIds(new ArrayList<>());
+        }
+        if (orderDto.getTransactionId() == null) {
+            orderDto.setTransactionId("N/A");
+        }
+        return orderDto;
+    }
+
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithDefault.java b/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithDefault.java
new file mode 100644
index 000000000000..0c1ffa7cf394
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/mapper/OrderMapperWithDefault.java
@@ -0,0 +1,23 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.OrderDto;
+import com.baeldung.entity.Order;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+
+@Mapper(uses = PaymentMapper.class)
+public interface OrderMapperWithDefault {
+
+    @Mapping(
+            source = "payment",
+            target = "paymentDto",
+            defaultExpression = "java(new com.baeldung.dto.PaymentDto())"
+    )
+    @Mapping(
+            source = "transactionId",
+            target = "transactionId",
+            defaultValue = "N/A"
+    )
+    OrderDto toDto(Order order);
+
+}
diff --git a/mapstruct-3/src/main/java/com/baeldung/mapper/PaymentMapper.java b/mapstruct-3/src/main/java/com/baeldung/mapper/PaymentMapper.java
new file mode 100644
index 000000000000..3fe1d8d9f321
--- /dev/null
+++ b/mapstruct-3/src/main/java/com/baeldung/mapper/PaymentMapper.java
@@ -0,0 +1,12 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.PaymentDto;
+import com.baeldung.entity.Payment;
+import org.mapstruct.Mapper;
+
+@Mapper
+public interface PaymentMapper {
+
+    PaymentDto toDto(Payment payment);
+
+}
diff --git a/mapstruct-3/src/test/java/com/baeldung/mapper/AncestorMapperUnitTest.java b/mapstruct-3/src/test/java/com/baeldung/mapper/AncestorMapperUnitTest.java
new file mode 100644
index 000000000000..c6163c286a73
--- /dev/null
+++ b/mapstruct-3/src/test/java/com/baeldung/mapper/AncestorMapperUnitTest.java
@@ -0,0 +1,42 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.AncestorDto;
+import com.baeldung.entity.GrandDad;
+import com.baeldung.entity.Identity;
+import org.junit.Test;
+import org.mapstruct.factory.Mappers;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class AncestorMapperUnitTest {
+
+    @Test
+    public void whenAncestorMapperToDtoMapsGrandad_thenSourceValuesAreUsed() {
+        AncestorMapper mapper = Mappers.getMapper(AncestorMapper.class);
+        GrandDad source = new GrandDad(
+                new Identity("Thomas", "Tom"),
+                "80.00",
+                "1234556"
+        );
+        AncestorDto mapped = mapper.toDto(source);
+        assertEquals("Thomas", mapped.getFirstName());
+        assertEquals(80.0d, mapped.getWeight(), 0.01d);
+        assertEquals("1234556", mapped.getVatNumber());
+    }
+
+    @Test
+    public void whenAncestorMapperToDtoMapsGrandadWithEmptyValues_thenNullValuesAreMapped() {
+        AncestorMapper mapper = Mappers.getMapper(AncestorMapper.class);
+        GrandDad source = new GrandDad(
+                null,
+                null,
+                "1234556"
+        );
+        AncestorDto mapped = mapper.toDto(source);
+        assertNull(mapped.getFirstName());
+        assertNull(mapped.getWeight());
+        assertEquals("1234556", mapped.getVatNumber());
+    }
+
+}
diff --git a/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithAfterMappingUnitTest.java b/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithAfterMappingUnitTest.java
new file mode 100644
index 000000000000..e6d6d91fbf9c
--- /dev/null
+++ b/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithAfterMappingUnitTest.java
@@ -0,0 +1,43 @@
+package com.baeldung.mapper;
+
+
+import com.baeldung.dto.OrderDto;
+import com.baeldung.entity.Order;
+import com.baeldung.entity.Payment;
+import org.junit.Test;
+import org.mapstruct.factory.Mappers;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+public class OrderMapperWithAfterMappingUnitTest {
+
+    @Test
+    public void whenOrderMapperWithAfterMappingToDtoMapsOrderWithEmptyProperties_thenDefaultValuesAreUsed() {
+        OrderMapperWithAfterMapping mapper = Mappers.getMapper(OrderMapperWithAfterMapping.class);
+        Order orderSource = new Order();
+        orderSource.setPayment(new Payment("Cash"));
+        OrderDto mapped = mapper.toDto(orderSource);
+        assertEquals("Cash", mapped.getPaymentDto().getType());
+        assertEquals("N/A", mapped.getTransactionId());
+        assertNotNull(mapped.getOrderItemIds());
+        assertEquals(0, mapped.getOrderItemIds().size());
+    }
+
+    @Test
+    public void whenOrderMapperWithAfterMappingToDtoMapsOrderWithNonEmptyProperties_thenSourceValuesAreUsed() {
+        OrderMapperWithAfterMapping mapper = Mappers.getMapper(OrderMapperWithAfterMapping.class);
+        Order orderSource = new Order();
+        orderSource.setPayment(new Payment("Cash"));
+        orderSource.setOrderItemIds(List.of("item1", "item2"));
+        orderSource.setTransactionId("orderTransaction");
+        OrderDto mapped = mapper.toDto(orderSource);
+        assertEquals("Cash", mapped.getPaymentDto().getType());
+        assertEquals("orderTransaction", mapped.getTransactionId());
+        assertNotNull(mapped.getOrderItemIds());
+        assertEquals(2, mapped.getOrderItemIds().size());
+    }
+
+}
diff --git a/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithDefaultUnitTest.java b/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithDefaultUnitTest.java
new file mode 100644
index 000000000000..9f8824213411
--- /dev/null
+++ b/mapstruct-3/src/test/java/com/baeldung/mapper/OrderMapperWithDefaultUnitTest.java
@@ -0,0 +1,40 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.OrderDto;
+import com.baeldung.entity.Order;
+import com.baeldung.entity.Payment;
+import org.junit.Test;
+import org.mapstruct.factory.Mappers;
+
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class OrderMapperWithDefaultUnitTest {
+
+    @Test
+    public void whenOrderMapperWithDefaultToDtoMapsOrderWithEmptyProperties_thenDefaultValuesAreUsed() {
+        OrderMapperWithDefault mapper = Mappers.getMapper(OrderMapperWithDefault.class);
+        Order orderSource = new Order();
+        orderSource.setPayment(new Payment("Cash"));
+        OrderDto mapped = mapper.toDto(orderSource);
+        assertEquals("Cash", mapped.getPaymentDto().getType());
+        assertEquals("N/A", mapped.getTransactionId());
+        assertNull(mapped.getOrderItemIds());
+    }
+
+    @Test
+    public void whenOrderMapperWithDefaultToDtoMapsOrderWithNonEmptyProperties_thenSourceValuesAreUsed() {
+        OrderMapperWithDefault mapper = Mappers.getMapper(OrderMapperWithDefault.class);
+        Order orderSource = new Order();
+        orderSource.setPayment(new Payment("Cash"));
+        orderSource.setOrderItemIds(List.of("item1", "item2"));
+        orderSource.setTransactionId("orderTransaction");
+        OrderDto mapped = mapper.toDto(orderSource);
+        assertEquals("Cash", mapped.getPaymentDto().getType());
+        assertEquals("orderTransaction", mapped.getTransactionId());
+        assertNotNull(mapped.getOrderItemIds());
+        assertEquals(2, mapped.getOrderItemIds().size());
+    }
+
+}