DataTable Row Group

@Named("dtRowGroupView")
@ViewScoped
public class RowGroupView implements Serializable {
    
    private List<Customer> customers;
    
    @Inject
    private CustomerService service;

    @PostConstruct
    public void init() {
        customers = service.getCustomers(50);
    }

    public long getTotalCount(String name) {
        return customers.stream().filter(customers -> name.equals(customers.representative.name)).count();
    }

    public List<Customer> getCustomers() {
        return customers;
    }

    public void setService(CustomerService service) {
        this.service = service;
    }
}

@Named
@ApplicationScoped
public class CustomerService {

    List<Customer> customers;
    private Country[] countries;
    private Representative[] representatives;
    private String[] names;
    private String[] companies;

    @PostConstruct
    public void init() {
        customers = new ArrayList<>();

        countries = new Country[]{
                new Country(0, "Argentina", "ar"),
                new Country(1, "Australia", "au"),
                new Country(2, "Brazil", "br"),
                new Country(3, "Canada", "ca"),
                new Country(4, "Germany", "de"),
                new Country(5, "France", "fr"),
                new Country(6, "India", "in"),
                new Country(7, "Italy", "it"),
                new Country(8, "Japan", "jp"),
                new Country(9, "Russia", "ru"),
                new Country(10, "Spain", "es"),
                new Country(11, "United Kingdom", "gb")};

        companies = new String[]{"Benton, John B Jr", "Chanay, Jeffrey A Esq", "Chemel, James L Cpa", "Feltz Printing Service",
                "Printing Dimensions", "Chapman, Ross E Esq", "Morlong Associates", "Commercial Press", "Truhlar And Truhlar Attys",
                "King, Christopher A Esq","Dorl, James J Esq","Rangoni Of Florence","Feiner Bros","Buckley Miller Wright","Rousseaux, Michael Esq",};

        representatives = new Representative[]{new Representative("Amy Elsner", "amyelsner.png"), new Representative("Anna Fali", "annafali.png"),
                new Representative("Asiya Javayant", "asiyajavayant.png"), new Representative("Bernardo Dominic", "bernardodominic.png"),
                new Representative("Elwin Sharvill", "elwinsharvill.png"), new Representative("Ioni Bowcher", "ionibowcher.png"),
                new Representative("Ivan Magalhaes", "ivanmagalhaes.png"), new Representative("Onyama Limba", "onyamalimba.png"),
                new Representative("Stephen Shaw", "stephenshaw.png"), new Representative("Xuxue Feng", "xuxuefeng.png")};

        names = new String[]{"James Butt", "David Darakjy", "Jeanfrancois Venere", "Ivar Paprocki", "Tony Foller",
                "Adams Morasca", "Claire Tollner", "Costa Dilliard", "Juan Wieser", "Maria Marrier", "Jennifer Amigon",
                "Stacey Maclead", "Leja Caldarera", "Morrow Ruta", "Arvin Albares", "Darci Poquette", "Izzy Garufi",
                "Ricardo Gaucho", "Clifford Rim", "Emily Whobrey", "Kadeem Flosi", "Mujtaba Nicka", "Aika Inouye",
                "Mayumi Kolmetz", "Misaki Royster", "Silvio Slusarski", "Nicolas Iturbide", "Antonio Caudy", "" +
                "Deepesh Chui", "Aditya Kusko", "Aruna Figeroa", "Jones Vocelka", "Julie Stenseth", "Smith Glick",
                "Johnson Sergi", "Francesco Shinko", "Salvatore Stockham", "Kaitlin Ostrosky", "Faith Gillian",
                "Maisha Rulapaugh", "Jefferson Schemmer", "Leon Oldroyd", "Rodrigues Campain", "Alejandro Perin",
                "Munro Ferencz", "Cody Saylors", "Chavez Briddick", "Sinclair Waycott", "Isabel Bowley", "Octavia Malet",
                "Murillo Malet", "Greenwood Bolognia", "Wickens Nestle", "Ashley Doe"};
    }


    public List<Customer> getCustomers(int number) {
        List<Customer> customers = new ArrayList<>();
        for (int i = 0; i < number; i++) {
            customers.add(new Customer(i + 1000, getName(), getCompany(), getCountry(), getDate(), CustomerStatus.random(), getActivity(), getRepresentative()));
        }
        return customers;
    }

    public List<Country> getCountries() {
        return Arrays.asList(countries);
    }

    public CustomerStatus[] getCustomerStatus() {
        return CustomerStatus.values();
    }

    public List<Representative> getRepresentatives() {
        return Arrays.asList(representatives);
    }

    private String getName() {
        return names[(int) (Math.random() * names.length)];
    }

    private Country getCountry() {
        return countries[(int) (Math.random() * countries.length)];
    }

    private String getCompany() {
        return companies[(int) (Math.random() * companies.length)];
    }

    private LocalDate getDate() {
        LocalDate now = LocalDate.now();
        long randomDay = ThreadLocalRandom.current().nextLong(now.minusDays(30).toEpochDay(), now.toEpochDay());
        return LocalDate.ofEpochDay(randomDay);
    }

    private int getActivity() {
        return (int) (Math.random() * 100);
    }

    private Representative getRepresentative() {
        return representatives[(int) (Math.random() * representatives.length)];
    }
}