JSpecify: Propagate nullability annotations to mapper implementation #4076

@Mapper
@NullMarked // or @NullMarked in package-info.java
public interface NullMarkedMapper {

    @Mapping(target = "foo", source = "source1.foo")
    @Mapping(target = "bar", source = "source1.bar")
    @Mapping(target = "baz", source = "source2.baz")
    Target map(Source1 source1, @Nullable Source2 source2);
}

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "0000-00-00T00:00:00+0000",
    comments = "version: , compiler: javac, environment: Java 21"
)
@NullMarked
public class NullMarkedMapperImpl implements NullMarkedMapper {

    @Override
    public Target map(Source1 source1, @Nullable Source2 source2) {

        Long baz = null;
        if ( source2 != null ) {
            baz = source2.getBaz();
        }
        String foo = null;
        foo = source1.getFoo();
        boolean bar = false;
        bar = source1.isBar();

        Target target = new Target( foo, bar, baz );

        return target;
    }
}