Setting nullValueMappingStrategy on the mapper / mapper config level for categories of mappings - mapstruct

Question

MapStruct documentation has the following to say about the sensible defaults chosen for NullValueMappingStrategy.RETURN_DEFAULT:
Bean mappings: an 'empty' target bean will be returned, with the
exception of constants and expressions, they will be populated when
present.
Primitives: the default values for primitives will be returned, e.g.
false for boolean or 0 for int.
Iterables / Arrays: an empty iterable will be returned.
Maps: an empty map will be returned.
The problem is, we want to be able specify on the #Mapper level that, e.g., Iterables should have NullValueMappingStrategy.RETURN_DEFAULT but not primitives. The reason for this is that an empty iterable is a sensible default for our use case, but 0 is not a sensible default for int. We'd prefer not to have to, e.g., declare:
#IterableMapping(nullValueMappingStrategy = NullValueMappingStrategy.RETURN_DEFAULT)
for every iterable we are mapping.
Does MapStruct provide a clean way to do this that I am not finding in the documentation?

Answer 1

I think the above line is actually a copy-paste error in the documentation. To make myself clear: the NullValueMappingStrategy only applies to arguments of mapping methods. Not to bean properties. It is not possible to define a primitive argument as source in a bean mapping method.
It is however possible to define non-beans as source of a bean mapping method. Like the mapFrom method below:
package org.mapstruct.ap.test.bugs._xyz;
import java.util.List;
import org.mapstruct.Mapper;
import org.mapstruct.NullValueMappingStrategy;
import org.mapstruct.factory.Mappers;
#Mapper( nullValueMappingStrategy = NullValueMappingStrategy.RETURN_DEFAULT)
public interface XyzMapper {
XyzMapper INSTANCE = Mappers.getMapper(XyzMapper.class);
Target map(Source source);
Target mapFrom( Integer myInt, List<Integer> myList);
class Source {
private int myInt;
private List<Integer> myList;
public int getMyInt() {
return myInt;
}
public void setMyInt(int myInt) {
this.myInt = myInt;
}
public List<Integer> getMyList() {
return myList;
}
public void setMyList(List<Integer> myList) {
this.myList = myList;
}
}
class Target {
private int myInt;
private List<Integer> myList;
public int getMyInt() {
return myInt;
}
public void setMyInt(int myInt) {
this.myInt = myInt;
}
public List<Integer> getMyList() {
return myList;
}
public void setMyList(List<Integer> myList) {
this.myList = myList;
}
}
}
When using the NullValueMappingStrategy.RETURN_DEFAULT the mapFrom will return an empty Target just as is specified in the documentation.
This line should be removed from the documentation in relation to the NullValueMappingStrategy: Primitives: the default values for primitives will be returned, e.g. false for boolean or 0 for int.