Convert delimited string columns to Integer list in JPA

AdSegment.java

@Slf4j
@Data
@Entity
@Table(name = "ad_segment")
public class AdSegment {

    @Id
    @GeneratedValue
    private long id;

    private long advertisement;
    @Convert(converter = DelimitedStringToIntListConverter.class)
    private List<Integer> segment;

    private boolean isExcluded;

}

AdSegmentationRepo.java

@Repository
public interface AdSegmentationRepo extends CrudRepository<AdSegment, Long>, QueryDslPredicateExecutor<AdSegment> {
}

AdSegmentTest.groovy

class AdSegmentTest extends Specification {
    static final def log = org.slf4j.LoggerFactory.getLogger(AdSegmentTest)
    static final long TARGET_AD_ID = 11

    @Shared
    DataSource datasource

    @Autowired
    ApplicationContext applicationContext

    @Shared
    AdSegmentationRepo adSegmentationRepo


 @DbUnit(configure = { IDatabaseTester it ->
        it.setUpOperation = DatabaseOperation.CLEAN_INSERT
        it.tearDownOperation = DatabaseOperation.TRUNCATE_TABLE
    })
    def adSegmentRows = {
        ad_segment(id: 1, advertisement: TARGET_AD_ID, segment: "111|222|333|444", is_excluded: false)
        ad_segment(id: 2, advertisement: TARGET_AD_ID, segment: "555|666|777|888", is_excluded: false)
        ad_segment(id: 3, advertisement: TARGET_AD_ID, segment: "111|222", is_excluded: true)
    }
    
    def setup() {
        datasource = applicationContext.getBean(DataSource.class)
        adSegmentationRepo = applicationContext.getBean(AdSegmentationRepo.class)
    }
    
        def "when loading AdSegment entity, entity's segment should be Integer List "() {

        expect:
        expectResult.containsAll(adSegmentationRepo.findOne(expectId).getSegment())
        where:
        expectId || expectResult
        1L || Lists.newArrayList(111,222,333,444)
    }

    
}

DelimitedStringToIntListConverter.java

@Converter
public class DelimitedStringToIntListConverter implements AttributeConverter<List<Integer>, String> {
    private static final Splitter splitter = Splitter.on("|").omitEmptyStrings();
    private static final Joiner joiner = Joiner.on("|").skipNulls();

    @Override
    public String convertToDatabaseColumn(List<Integer> attribute) {
        return joiner.join(attribute);
    }

    @Override
    public List<Integer> convertToEntityAttribute(String dbData) {
        return splitter.splitToList(dbData).stream()
                .map(Integer::valueOf)
                .collect(Collectors.toList());
    }
}