#765 Omitting "return" key word when returning from decorated void method

processor/src/main/resources/org/mapstruct/ap/internal/model/DelegatingMethod.ftl

@@ -20,7 +20,7 @@
 -->
 @Override
 public <@includeModel object=returnType/> ${name}(<#list parameters as param><@includeModel object=param/><#if param_has_next>, </#if></#list>) <@throws/> {
-    return delegate.${name}( <#list parameters as param>${param.name}<#if param_has_next>, </#if></#list> );
+    <#if returnType.name != "void">return </#if>delegate.${name}( <#list parameters as param>${param.name}<#if param_has_next>, </#if></#list> );
 }
 <#macro throws>
     <@compress single_line=true>

processor/src/test/java/org/mapstruct/ap/test/decorator/AddressDto.java

@@ -22,6 +22,13 @@ public class AddressDto {
 
     private String addressLine;
 
+    public AddressDto() {
+    }
+
+    public AddressDto(String addressLine) {
+        this.addressLine = addressLine;
+    }
+
     public String getAddressLine() {
         return addressLine;
     }

processor/src/test/java/org/mapstruct/ap/test/decorator/DecoratorTest.java

@@ -86,6 +86,24 @@ public class DecoratorTest {
         assertThat( addressDto.getAddressLine() ).isEqualTo( "42 Ocean View Drive" );
     }
 
+    @Test
+    @WithClasses({
+        PersonMapper.class,
+        PersonMapperDecorator.class
+    })
+    @IssueKey("765")
+    public void shouldDelegateNonDecoratedVoidMethodsToDefaultImplementation() {
+        //given
+        AddressDto addressDto = new AddressDto( "42 Ocean View Drive" );
+
+        //when
+        Address address = new Address( "Main Street" );
+        PersonMapper.INSTANCE.updateAddressFromDto( addressDto, address );
+
+        //then
+        assertThat( address.getAddressLine() ).isEqualTo( "42 Ocean View Drive" );
+    }
+
     @Test
     @WithClasses({
         AnotherPersonMapper.class,

processor/src/test/java/org/mapstruct/ap/test/decorator/PersonMapper.java

@@ -21,6 +21,7 @@ package org.mapstruct.ap.test.decorator;
 import org.mapstruct.DecoratedWith;
 import org.mapstruct.Mapper;
 import org.mapstruct.Mapping;
+import org.mapstruct.MappingTarget;
 import org.mapstruct.factory.Mappers;
 
 @Mapper
@@ -33,4 +34,6 @@ public interface PersonMapper {
     PersonDto personToPersonDto(Person person);
 
     AddressDto addressToAddressDto(Address address);
+
+    void updateAddressFromDto(AddressDto dto, @MappingTarget Address address);
 }