Код-ревью: сборщик отчётов

@Component
@Scope("prototype")
public class ReportBuilder {
    private final List<String> rows = new ArrayList<>();
    public void add(String row) { rows.add(row); }
    public String build() { return String.join("\n", rows); }
}

@Service
public class ReportService {
    private final ReportBuilder builder;
    private final ReportRepository repo;
    private int generated;
    private final SimpleDateFormat fmt = new SimpleDateFormat("dd.MM.yyyy");

    public ReportService(ReportBuilder builder, ReportRepository repo) {
        this.builder = builder;
        this.repo = repo;
    }

    @PostConstruct
    @Transactional
    public void warmUp() {
        repo.preloadTemplates();
    }

    public String daily(LocalDate day) {
        generated++;
        builder.add("Отчёт за " + fmt.format(java.sql.Date.valueOf(day)));
        repo.findRows(day).forEach(builder::add);
        return builder.build();
    }
}