mapstruct · hduelme · Mar 29, 2026 · Mar 30, 2026
diff --git a/...apstruct/ap/internal/model/assignment/SetterWrapperForCollectionsAndMapsWithNullCheck.ftl b/...apstruct/ap/internal/model/assignment/SetterWrapperForCollectionsAndMapsWithNullCheck.ftl
@@ -26,6 +26,6 @@
     <#if enumSet>
       EnumSet.copyOf( ${nullCheckLocalVarName} )
     <#else>
-      new <#if ext.targetType.implementationType??><@includeModel object=ext.targetType.implementationType/><#else><@includeModel object=ext.targetType/></#if>( ${nullCheckLocalVarName} )
+      new <#if ext.targetType.implementationType??><@includeModel object=ext.targetType.implementationType useDiamondOperator=true/><#else><@includeModel object=ext.targetType/></#if>( ${nullCheckLocalVarName} )
     </#if>
 </@compress></#macro>
diff --git a/processor/src/main/resources/org/mapstruct/ap/internal/model/common/Type.ftl b/processor/src/main/resources/org/mapstruct/ap/internal/model/common/Type.ftl
@@ -12,6 +12,6 @@
     <#elseif hasSuperBound()>
         ? super <@includeModel object=typeBound />
     <#else>
-        <#if ext.asVarArgs!false>${createReferenceName()?remove_ending("[]")}...<#else>${createReferenceName()}</#if></#if><#if (!ext.raw?? && typeParameters?size > 0) ><<#list typeParameters as typeParameter><@includeModel object=typeParameter /><#if typeParameter_has_next>, </#if></#list>>
+        <#if ext.asVarArgs!false>${createReferenceName()?remove_ending("[]")}...<#else>${createReferenceName()}</#if></#if><#if (!ext.raw?? && typeParameters?size > 0) ><<#if !ext.useDiamondOperator??><#list typeParameters as typeParameter><@includeModel object=typeParameter /><#if typeParameter_has_next>, </#if></#list></#if>>
     </#if>
 </@compress>
diff --git a/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/BoundCopyMapper.java b/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/BoundCopyMapper.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.generics.wildcard;
+
+import org.mapstruct.Mapper;
+
+@Mapper
+public interface BoundCopyMapper {
+
+    CollectionSuperTypes copySuperCollection(CollectionSuperTypes collectionSuperTypes);
+
+    CollectionExtendTypes copyExtendsCollection(CollectionExtendTypes collectionExtendTypes);
+
+    MapSuperType copySuperMap(MapSuperType mapSuperType);
+
+    MapExtendType copyExtendMap(MapExtendType mapExtendType);
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/BoundDirectCopyTest.java b/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/BoundDirectCopyTest.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.generics.wildcard;
+
+import org.junit.jupiter.api.extension.RegisterExtension;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.GeneratedSource;
+
+/**
+ * @author hduelme
+ *
+ */
+public class BoundDirectCopyTest {
+
+    @RegisterExtension
+    final GeneratedSource generatedSource = new GeneratedSource().addComparisonToFixtureFor(
+            BoundCopyMapper.class
+    );
+
+    @ProcessorTest
+    @WithClasses({
+            SimpleObject.class,
+            CollectionSuperTypes.class,
+            CollectionExtendTypes.class,
+            MapSuperType.class,
+            MapExtendType.class,
+            BoundCopyMapper.class
+    })
+    public void shouldCopyBoundedDirectly() {
+
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/MapExtendType.java b/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/MapExtendType.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.generics.wildcard;
+
+import java.util.Map;
+
+public class MapExtendType {
+
+    private Map<? extends SimpleObject, ? extends SimpleObject> simpleMap;
+
+    public Map<? extends SimpleObject, ? extends SimpleObject> getSimpleMap() {
+        return simpleMap;
+    }
+
+    public void setSimpleMap(
+            Map<? extends SimpleObject, ? extends SimpleObject> simpleMap) {
+        this.simpleMap = simpleMap;
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/MapSuperType.java b/processor/src/test/java/org/mapstruct/ap/test/generics/wildcard/MapSuperType.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.generics.wildcard;
+
+import java.util.Map;
+
+public class MapSuperType {
+
+    private Map<? super SimpleObject, ? super SimpleObject> simpleMap;
+
+    public Map<? super SimpleObject, ? super SimpleObject> getSimpleMap() {
+        return simpleMap;
+    }
+
+    public void setSimpleMap(
+            Map<? super SimpleObject, ? super SimpleObject> simpleMap) {
+        this.simpleMap = simpleMap;
+    }
+}
diff --git a/...ources/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNcvsAlwaysMapperImpl.java b/...ources/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNcvsAlwaysMapperImpl.java
@@ -30,21 +30,21 @@ public Domain create(DtoWithPresenceCheck source) {
 
         if ( source.hasStrings() ) {
             List<String> list = source.getStrings();
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         if ( source.hasStrings() ) {
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
         }
         if ( source.hasStringsInitialized() ) {
             List<String> list1 = source.getStringsInitialized();
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         if ( source.hasStringsInitialized() ) {
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         }
         if ( source.hasStringsWithDefault() ) {
             List<String> list2 = source.getStringsWithDefault();
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...urces/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsDefaultMapperImpl.java b/...urces/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsDefaultMapperImpl.java
@@ -28,17 +28,17 @@ public Domain create(Dto source) {
         if ( source != null ) {
             List<String> list = source.getStrings();
             if ( list != null ) {
-                domain.setStrings( new LinkedHashSet<String>( list ) );
+                domain.setStrings( new LinkedHashSet<>( list ) );
             }
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
             List<String> list1 = source.getStringsInitialized();
             if ( list1 != null ) {
-                domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+                domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
             }
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
             List<String> list2 = source.getStringsWithDefault();
             if ( list2 != null ) {
-                domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+                domain.setStringsWithDefault( new ArrayList<>( list2 ) );
             }
             else {
                 domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...esources/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsNullMapperImpl.java b/...esources/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsNullMapperImpl.java
@@ -30,17 +30,17 @@ public Domain create(Dto source) {
 
         List<String> list = source.getStrings();
         if ( list != null ) {
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         domain.setLongs( stringListToLongSet( source.getStrings() ) );
         List<String> list1 = source.getStringsInitialized();
         if ( list1 != null ) {
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         List<String> list2 = source.getStringsWithDefault();
         if ( list2 != null ) {
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...ces/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithPresenceCheckMapperImpl.java b/...ces/fixtures/21/org/mapstruct/ap/test/bugs/_913/DomainDtoWithPresenceCheckMapperImpl.java
@@ -30,21 +30,21 @@ public Domain create(DtoWithPresenceCheck source) {
 
         if ( source.hasStrings() ) {
             List<String> list = source.getStrings();
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         if ( source.hasStrings() ) {
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
         }
         if ( source.hasStringsInitialized() ) {
             List<String> list1 = source.getStringsInitialized();
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         if ( source.hasStringsInitialized() ) {
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         }
         if ( source.hasStringsWithDefault() ) {
             List<String> list2 = source.getStringsWithDefault();
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/processor/src/test/resources/fixtures/org/mapstruct/ap/test/bugs/_1685/UserMapperImpl.java b/processor/src/test/resources/fixtures/org/mapstruct/ap/test/bugs/_1685/UserMapperImpl.java
@@ -157,7 +157,7 @@ protected ContactDataDTO userToContactDataDTO(User user) {
         contactDataDTO.setAddress( user.getAddress() );
         List<String> list = user.getPreferences();
         if ( list != null ) {
-            contactDataDTO.setPreferences( new ArrayList<String>( list ) );
+            contactDataDTO.setPreferences( new ArrayList<>( list ) );
         }
         String[] settings = user.getSettings();
         if ( settings != null ) {

diff --git a/...resources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNcvsAlwaysMapperImpl.java b/...resources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNcvsAlwaysMapperImpl.java
@@ -30,21 +30,21 @@ public Domain create(DtoWithPresenceCheck source) {
 
         if ( source.hasStrings() ) {
             List<String> list = source.getStrings();
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         if ( source.hasStrings() ) {
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
         }
         if ( source.hasStringsInitialized() ) {
             List<String> list1 = source.getStringsInitialized();
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         if ( source.hasStringsInitialized() ) {
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         }
         if ( source.hasStringsWithDefault() ) {
             List<String> list2 = source.getStringsWithDefault();
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...esources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsDefaultMapperImpl.java b/...esources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsDefaultMapperImpl.java
@@ -28,17 +28,17 @@ public Domain create(Dto source) {
         if ( source != null ) {
             List<String> list = source.getStrings();
             if ( list != null ) {
-                domain.setStrings( new LinkedHashSet<String>( list ) );
+                domain.setStrings( new LinkedHashSet<>( list ) );
             }
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
             List<String> list1 = source.getStringsInitialized();
             if ( list1 != null ) {
-                domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+                domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
             }
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
             List<String> list2 = source.getStringsWithDefault();
             if ( list2 != null ) {
-                domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+                domain.setStringsWithDefault( new ArrayList<>( list2 ) );
             }
             else {
                 domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...t/resources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsNullMapperImpl.java b/...t/resources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithNvmsNullMapperImpl.java
@@ -30,17 +30,17 @@ public Domain create(Dto source) {
 
         List<String> list = source.getStrings();
         if ( list != null ) {
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         domain.setLongs( stringListToLongSet( source.getStrings() ) );
         List<String> list1 = source.getStringsInitialized();
         if ( list1 != null ) {
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         List<String> list2 = source.getStringsWithDefault();
         if ( list2 != null ) {
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/...ources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithPresenceCheckMapperImpl.java b/...ources/fixtures/org/mapstruct/ap/test/bugs/_913/DomainDtoWithPresenceCheckMapperImpl.java
@@ -30,21 +30,21 @@ public Domain create(DtoWithPresenceCheck source) {
 
         if ( source.hasStrings() ) {
             List<String> list = source.getStrings();
-            domain.setStrings( new LinkedHashSet<String>( list ) );
+            domain.setStrings( new LinkedHashSet<>( list ) );
         }
         if ( source.hasStrings() ) {
             domain.setLongs( stringListToLongSet( source.getStrings() ) );
         }
         if ( source.hasStringsInitialized() ) {
             List<String> list1 = source.getStringsInitialized();
-            domain.setStringsInitialized( new LinkedHashSet<String>( list1 ) );
+            domain.setStringsInitialized( new LinkedHashSet<>( list1 ) );
         }
         if ( source.hasStringsInitialized() ) {
             domain.setLongsInitialized( stringListToLongSet( source.getStringsInitialized() ) );
         }
         if ( source.hasStringsWithDefault() ) {
             List<String> list2 = source.getStringsWithDefault();
-            domain.setStringsWithDefault( new ArrayList<String>( list2 ) );
+            domain.setStringsWithDefault( new ArrayList<>( list2 ) );
         }
         else {
             domain.setStringsWithDefault( helper.toList( "3" ) );

diff --git a/.../test/resources/fixtures/org/mapstruct/ap/test/generics/wildcard/BoundCopyMapperImpl.java b/.../test/resources/fixtures/org/mapstruct/ap/test/generics/wildcard/BoundCopyMapperImpl.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.generics.wildcard;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import javax.annotation.processing.Generated;
+
+@Generated(
+    value = "org.mapstruct.ap.MappingProcessor",
+    date = "2026-03-30T02:05:36+0200",
+    comments = "version: , compiler: javac, environment: Java 21.0.5 (Eclipse Adoptium)"
+)
+public class BoundCopyMapperImpl implements BoundCopyMapper {
+
+    @Override
+    public CollectionSuperTypes copySuperCollection(CollectionSuperTypes collectionSuperTypes) {
+        if ( collectionSuperTypes == null ) {
+            return null;
+        }
+
+        CollectionSuperTypes collectionSuperTypes1 = new CollectionSuperTypes();
+
+        Collection<? super SimpleObject> collection = collectionSuperTypes.getSimpleObjectsCollection();
+        if ( collection != null ) {
+            collectionSuperTypes1.setSimpleObjectsCollection( new ArrayList<>( collection ) );
+        }
+
+        return collectionSuperTypes1;
+    }
+
+    @Override
+    public CollectionExtendTypes copyExtendsCollection(CollectionExtendTypes collectionExtendTypes) {
+        if ( collectionExtendTypes == null ) {
+            return null;
+        }
+
+        CollectionExtendTypes collectionExtendTypes1 = new CollectionExtendTypes();
+
+        Collection<? extends SimpleObject> collection = collectionExtendTypes.getSimpleObjectsCollection();
+        if ( collection != null ) {
+            collectionExtendTypes1.setSimpleObjectsCollection( new ArrayList<>( collection ) );
+        }
+
+        return collectionExtendTypes1;
+    }
+
+    @Override
+    public MapSuperType copySuperMap(MapSuperType mapSuperType) {
+        if ( mapSuperType == null ) {
+            return null;
+        }
+
+        MapSuperType mapSuperType1 = new MapSuperType();
+
+        Map<? super SimpleObject, ? super SimpleObject> map = mapSuperType.getSimpleMap();
+        if ( map != null ) {
+            mapSuperType1.setSimpleMap( new LinkedHashMap<>( map ) );
+        }
+
+        return mapSuperType1;
+    }
+
+    @Override
+    public MapExtendType copyExtendMap(MapExtendType mapExtendType) {
+        if ( mapExtendType == null ) {
+            return null;
+        }
+
+        MapExtendType mapExtendType1 = new MapExtendType();
+
+        Map<? extends SimpleObject, ? extends SimpleObject> map = mapExtendType.getSimpleMap();
+        if ( map != null ) {
+            mapExtendType1.setSimpleMap( new LinkedHashMap<>( map ) );
+        }
+
+        return mapExtendType1;
+    }
+}