import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.ReportingPolicy;
import org.mapstruct.SubclassMapping;

@Mapper(unmappedTargetPolicy = ReportingPolicy.WARN)
public interface TestMapping {

  sealed interface From permits FromA, FromB {}

  record FromA(int a) implements From {}

  record FromB(int b) implements From {}

  record To(int to) {}

  @Mapping(source = "a", target = "to")
  To map(FromA from);

  @Mapping(source = "b", target = "to")
  To map(FromB fromB);

  @SubclassMapping(source = FromA.class, target = To.class)
  @SubclassMapping(source = FromB.class, target = To.class)
  To map(From from);

}