System.Net.Http.Headers.WarningHeaderValue.CheckAgent C# (CSharp) Method

        private static void CheckAgent(string agent)
        {
            if (string.IsNullOrEmpty(agent))
            {
                throw new ArgumentException(SR.net_http_argument_empty_string, nameof(agent));
            }

            // 'receivedBy' can either be a host or a token. Since a token is a valid host, we only verify if the value
            // is a valid host.
            string host = null;
            if (HttpRuleParser.GetHostLength(agent, 0, true, out host) != agent.Length)
            {
                throw new FormatException(string.Format(System.Globalization.CultureInfo.InvariantCulture, SR.net_http_headers_invalid_value, agent));
            }
        }
    }