ServiceStack.HttpRequestExtensions.HasNotModifiedSince C# (CSharp) Метод

        public static bool HasNotModifiedSince(this IRequest httpReq, DateTime? dateTime)
        {
            if (!dateTime.HasValue) return false;
            var strHeader = httpReq.Headers[HttpHeaders.IfModifiedSince];
            try
            {
                if (strHeader != null)
                {
                    var dateIfModifiedSince = DateTime.ParseExact(strHeader, "r", null);
                    var utcFromDate = dateTime.Value.ToUniversalTime();
                    //strip ms
                    utcFromDate = new DateTime(
                        utcFromDate.Ticks - (utcFromDate.Ticks % TimeSpan.TicksPerSecond),
                        utcFromDate.Kind
                    );

                    return utcFromDate <= dateIfModifiedSince;
                }
                return false;
            }
            catch
            {
                return false;
            }
        }