internal DiagnosticsFragment(DiagnosticsContext context, string category)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            if (category == null)
                throw new ArgumentNullException("category");

            this.context = context;
            this.category = category;

            stopwatch = Stopwatch.StartNew();
        }
        internal DiagnosticsFragment(DiagnosticsContext context, string category)
        {
            if (context == null)
            {
                throw new ArgumentNullException("context");
            }
            if (category == null)
            {
                throw new ArgumentNullException("category");
            }

            this.context  = context;
            this.category = category;

            stopwatch = Stopwatch.StartNew();
        }