@SpringBootApplication
public class ReservationServiceApplication {

    @Bean
    CommandLineRunner commandLineRunner(ReservationRepository reservationRepository) {
        return strings -> {
            Stream.of("A","b","C","D", "I")
                    .forEach( n -> reservationRepository.save(new Reservation(n)));
        };
    }
    public static void main(String[] args) {
        SpringApplication.run(ReservationServiceApplication.class, args);
    }

}

@Entity
class Reservation {
    @Id
    @GeneratedValue
    private Long id;
    private  String reservationName;

    public Reservation(String reservationName) {
        this.reservationName = reservationName;
    }

    public Reservation() {
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getReservationName() {
        return reservationName;
    }

    public void setReservationName(String reservationName) {
        this.reservationName = reservationName;
    }

    @Override
    public String toString() {
        return "Reservation{" +
                "id=" + id +
                ", reservationName='" + reservationName + ''' +
                '}';
    }
}

@RepositoryRestResource
interface ReservationRepository extends JpaRepository<Reservation,Long> {
    @RestResource(path = "by-name")
    Collection<Reservation> findByREservationName(@Param("rn") String rn);
}