public async Task <ActionResult <CertificateViewModel> > GetCertificate(long id)
        {
            var certificate = await certificateRepository.GetByIdAsync(id);

            if (certificate == null)
            {
                return(NotFound($"Certificate with ID = {id} not found"));
            }

            var certificateViewModel = mapper.Map <CertificateViewModel>(certificate);

            return(certificateViewModel);
        }