NullValuePropertyMappingStrategy#IGNORE is not properly applied on maps / collections without setters #3806
Description
Expected behavior
I would expect that when mapping for Map attribute that has getter in destination but no setter will get similar implementation as for Map that has both setter and getter, especially when null attributes should be ignored as declare in examples below. Lets assume these types and mapper:
public interface DestinationType {
void addAttribute(String key, String value);
Map<String, String> getAttributes();
Map<String, String> getOthers();
void setOthers(Map<String, String> others);
}
public class SourceType {
Map<String, String> attributes = new HashMap<>();
Map<String, String> others = new HashMap<>();
public Map<String, String> getAttributes() {
return attributes;
}
public void setAttributes(Map<String, String> attributes) {
this.attributes = attributes;
}
public Map<String, String> getOthers() {
return others;
}
public void setOthers(Map<String, String> others) {
this.others = others;
}
}
@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE,
nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE,
nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS)
public interface MyMapper{
void update(@MappingTarget DestinationType destination, SourceType source);
}Actual behavior
When I change MyMapperImpl I can see:
@Generated(
value = "org.mapstruct.ap.MappingProcessor",
date = "2025-01-21T13:46:15+0100",
comments = "version: 1.6.3, compiler: javac, environment: Java 21.0.1 (Azul Systems, Inc.)"
)
public class MyMapperImpl implements MyMapper {
@Override
public void update(DestinationType destination, SourceType source) {
if ( source == null ) {
return;
}
if ( destination.getOthers() != null ) {
Map<String, String> map = source.getOthers();
if ( map != null ) {
destination.getOthers().clear();
destination.getOthers().putAll( map );
}
}
else {
Map<String, String> map = source.getOthers();
if ( map != null ) {
destination.setOthers( new LinkedHashMap<String, String>( map ) );
}
}
if ( destination.getAttributes() != null ) {
destination.getAttributes().clear();
Map<String, String> map1 = source.getAttributes();
if ( map1 != null ) {
destination.getAttributes().putAll( map1 );
}
}
}
}the biggest difference is clearing the destination collection. For others map we can see the "ignoring" as destination is untouched when source is null but for attributes map, there is clear always, which breaks the "ignoring" rule.
Maybe I get something wrong, but I am at the end with ideas.
Steps to reproduce the problem
Described above
MapStruct Version
1.6.3