Modelmapper skip a object field

Question

I have four class

public class A {

    private String field1;
    private String field2;

    private B b;

   // setter and getter
}

public class B {

    private String fieldB1;
    private String fieldB2;

   // setter and getter

}

public class ADto {

    private String field1;
    private String field2;

    private BDto b;

   // setter and getter
}

public class BDto {

    private String fieldB1;
    private String fieldB2;

   // setter and getter

}

I want to use modelmapper to populate dto objects

ModelMapper modelMapper = new ModelMapper();
modelMapper.typeMap(A.class, ADto.class, "LAZY")                
                .addMappings(mapper -> mapper.skip(ADto::setB))
                .addMappings(mapper -> mapper.skip(ADto::setField2));

modelMapper.map(a, ADto.class, "LAZY");

I use typeMapName to be able to have more mappers

The mapper correctly skips field2 but instead ignores the skip for B, what am I wrong?

Thanks