#3104 Update methods with NullValuePropertyMappingStrategy.IGNORE should use SetterWrapperForCollectionsAndMapsWithNullCheck

processor/src/main/java/org/mapstruct/ap/internal/model/CollectionAssignmentBuilder.java

@@ -31,6 +31,7 @@ import org.mapstruct.ap.internal.util.accessor.Accessor;
 import org.mapstruct.ap.internal.util.accessor.AccessorType;
 
 import static org.mapstruct.ap.internal.gem.NullValueCheckStrategyGem.ALWAYS;
+import static org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem.IGNORE;
 import static org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem.SET_TO_DEFAULT;
 import static org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem.SET_TO_NULL;
 
@@ -177,6 +178,16 @@ public class CollectionAssignmentBuilder {
                     targetAccessorType.isFieldAssignment()
                 );
             }
+            else if ( method.isUpdateMethod() && nvpms == IGNORE ) {
+
+                result = new SetterWrapperForCollectionsAndMapsWithNullCheck(
+                    result,
+                    method.getThrownTypes(),
+                    targetType,
+                    ctx.getTypeFactory(),
+                    targetAccessorType.isFieldAssignment()
+                );
+            }
             else if ( setterWrapperNeedsSourceNullCheck( result )
                 && canBeMappedOrDirectlyAssigned( result ) ) {
 

processor/src/test/java/org/mapstruct/ap/test/bugs/_3104/Issue3104Mapper.java

@@ -0,0 +1,77 @@
+/*
+ * 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.bugs._3104;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.MappingTarget;
+import org.mapstruct.NullValuePropertyMappingStrategy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.TARGET_IMMUTABLE)
+public interface Issue3104Mapper {
+
+    Issue3104Mapper INSTANCE = Mappers.getMapper( Issue3104Mapper.class );
+
+    @BeanMapping(nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
+    void update(@MappingTarget Target target, Source source);
+
+    class Target {
+        private List<Child> children = Collections.emptyList();
+
+        public List<Child> getChildren() {
+            return children;
+        }
+
+        public void setChildren(List<Child> children) {
+            if ( children == null ) {
+                throw new IllegalArgumentException( "children is null" );
+            }
+            this.children = Collections.unmodifiableList( children );
+        }
+    }
+
+    class Child {
+        private String myField;
+
+        public String getMyField() {
+            return myField;
+        }
+
+        public void setMyField(String myField) {
+            this.myField = myField;
+        }
+    }
+
+    class Source {
+        private final List<ChildSource> children;
+
+        public Source(List<ChildSource> children) {
+            this.children = children;
+        }
+
+        public List<ChildSource> getChildren() {
+            return children;
+        }
+
+    }
+
+    class ChildSource {
+        private final String myField;
+
+        public ChildSource(String myField) {
+            this.myField = myField;
+        }
+
+        public String getMyField() {
+            return myField;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_3104/Issue3104Test.java

@@ -0,0 +1,38 @@
+/*
+ * 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.bugs._3104;
+
+import java.util.Collections;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Filip Hrisafov
+ */
+@IssueKey("3104")
+@WithClasses(Issue3104Mapper.class)
+class Issue3104Test {
+
+    @ProcessorTest
+    void shouldCorrectlyMapUpdateMappingWithTargetImmutableCollectionStrategy() {
+        Issue3104Mapper.Target target = new Issue3104Mapper.Target();
+        Issue3104Mapper.INSTANCE.update( target, new Issue3104Mapper.Source( null ) );
+
+        assertThat( target.getChildren() ).isEmpty();
+
+        Issue3104Mapper.INSTANCE.update(
+            target,
+            new Issue3104Mapper.Source( Collections.singletonList( new Issue3104Mapper.ChildSource( "tester" ) ) )
+        );
+        assertThat( target.getChildren() )
+            .extracting( Issue3104Mapper.Child::getMyField )
+            .containsExactly( "tester" );
+    }
+}