public async Task <MimeFile> AddCertificate(CertificateEntity data)
        {
            var existing = cache.Get <MimeFile>(data.RowKey);

            if (existing != null)
            {
                throw new DuplicateTableRowException();
            }

            logger.LogInformation("Storing certificate " + data.RowKey);
            await tableStore.InsertRow(TABLE_NAME, data);

            var pdf = RenderCertificate(data);

            return(pdf);
        }