Redundant null checks for nested properties

Expected behavior

Consider this simple DTO and Entity classes:

@Data
public class PersonDTO {
    private String name;
    private String parentName;
}

@Data
public class Person {
    private String name;
    private Person parent;
}

And a simple mapper:

@Mapper
public interface PersonMapper {

    @Mapping(target = "parentName", source = "parent.name")
    PersonDTO entityToDTO(Person person);
}

Generated code should be:

public class PersonMapperImpl implements PersonMapper {

    @Override
    public PersonDTO entityToDTO(Person person) {
        if ( person == null ) {
            return null;
        }

        PersonDTO personDTO = new PersonDTO();

        personDTO.setParentName( personParentName( person ) );
        personDTO.setName( person.getName() );

        return personDTO;
    }

    private String personParentName(Person person) {
        Person parent = person.getParent();
        if ( parent == null ) {
            return null;
        }
        return parent.getName();
    }

Actual behavior

Generated code is this:

public class PersonMapperImpl implements PersonMapper {

    @Override
    public PersonDTO entityToDTO(Person person) {
        if ( person == null ) {
            return null;
        }

        PersonDTO personDTO = new PersonDTO();

        personDTO.setParentName( personParentName( person ) );
        personDTO.setName( person.getName() );

        return personDTO;
    }

    private String personParentName(Person person) {
        if ( person == null ) {       // Redundant null check, unreachable return statement
            return null;
        }
        Person parent = person.getParent();
        if ( parent == null ) {
            return null;
        }
        String name = parent.getName();
        if ( name == null ) {      // Redundant null check, just return the parent name
            return null;
        }
        return name;
    }

As marked, two additional redundant null checks were generated. The first one makes it impossible to reach full code coverage (unless using Reflection) and the second is just unnecessary code.

Steps to reproduce the problem

No special configuration needed to reproduce this.

MapStruct Version

MapStruct 1.5.4.Final