Mapstruct doesn't use custom enum mapper

Expected behavior

public interface CarMapper {

  CarDto carToCarDto(Car car);

  CarDtoEnum from(CarEnum carEnum);
}

should generate something like:

public class CarMapperImpl implements CarMapper {
  @Override
  public CarDto carToCarDto(Car car) {
     ...
      carDto.setCarDtoEnum(from(car.getCarEnum()));
   }
}

Actual behavior

public class CarMapperImpl implements CarMapper {
  @Override
  public CarDto carToCarDto(Car car) {
     ...
      carDto.setCarDtoEnum(Enum.valueOf(CarDtoEnum.class, car.getCarEnum()));
   }
}

Steps to reproduce the problem

see above description.

MapStruct Version

1.5.2.Final

Start by reproducing the issue with the CarMapper, Car, CarDto, CarEnum, and CarDtoEnum types shown in the report, then inspect the generated CarMapperImpl. Trace why enum mapping selects Enum.valueOf instead of the declared from(CarEnum) method; done when the generated mapper invokes that custom method.