MapStruct - Nested mapping

I need to map a response from third party API to another response structure. I'm using Mapstruct for that.

ThirdParty API classes :

public class TPResponse {
     protected UserListsType userLists;
     protected ProductOffers offers;
     //getters and setters
}

public class UserListsType {
    protected UserTypes userTypes;
    ...............
}

public class UserTypes{
    protected List<User> userType;
}

public class User{
 protected String userID;
}

public class ProductOffers {
    protected List<OffersType> OffersType;
}

public class OffersType{
   protected PriceType totalPrice;
}

Our API classes :

public class ActualResponse {
       private List<Customer> user = new ArrayList<Customer>();
       //getters and setters
    }

  public class Customer{
        private String customerId;
        private String pdtPrice;
        private OfferPrice offerPrice;
    }
   public class OfferPrice{
        private String offerId;
  }

I want to map these elements using MapStruct.

1) customerId <Map with> UserTypes->User->userID
2) pdtPrice  <Map with>  offers -> OffersType -> totalPrice
3) offerId  <Map with> sum of (offers -> OffersType -> totalPrice)

I tried to write Mapper Class using MapStruct like :

@Mapper(nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
public interface UserResponseMapper {
    UserResponseMapper RESPONSE_MAPPER = Mappers.getMapper(UserResponseMapper.class);

    @Mappings({
            @Mapping(target="customer.customerId", source="userTypes.userType.userId")
    })
    ActualResponse mapUser(UserListsType userListType);

}

Currently it shows the error like "Unknown property "customer.customerId" and "userTypes.userType.userId". Can anyone please help me to map all those elements using Mapstruct?

Question no 2 : How can we map following?
1) customerId <Map with> UserTypes->User->userID
2) pdtPrice <Map with> offers -> OffersType -> totalPrice
3) offerId <Map with> sum of (offers -> OffersType -> totalPrice)

I tried

@Mapping(target = "customerId", source = "userId")
@Mapping(target = "pdtPrice", source = "totalPrice")
    User mapUser(UserListsType userListType, OffersType offersType );

I'm getting null values for customerId and pdtPrice

From what I can understand you need to map the lists in ActualResponse and UserTypeListType.

When you provide a mapping between certain objects MapStruct can automatically generate mapping between its collections. So in your case you'll need to do something like:

@Mapper(nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
public interface UserResponseMapper {
    UserResponseMapper RESPONSE_MAPPER = Mappers.getMapper(UserResponseMapper.class);

    @Mappings({
            @Mapping(target="user", source="userType")
    })
    ActualResponse mapUser(UserTypeListType userListType);

    @Mapping(target = "customerId", source = "userId")
    User mapUser(UserType userType);

}

If you need to do calculations and have objects from different levels and you need to do some groupings and or aggregations I would suggest that you write your own logic.