Наследование: ConfigurationSection
        public static void RegisterRedirectHandler(this EditableXmlConfigHelper configHelper, string name, string redirectHandlerPath, string fullTypeName)
        {
            // Because the "system.webServer" ConfigurationSection is an IgnoreSection, it must be modified
            // using the raw XML.

            ConfigurationSection webServerSection = configHelper.Configuration.GetSection(ConfigHelperExtensions.WebServerSectionName);
            if (webServerSection == null)
            {
                webServerSection = new IgnoreSection();
                configHelper.Configuration.Sections.Add(ConfigHelperExtensions.WebServerSectionName, webServerSection);
            }

            XElement webServerElement;
            string webServerSectionRawXml = webServerSection.SectionInformation.GetRawXml();
            if (webServerSectionRawXml == null)
            {
                webServerElement = new XElement(ConfigHelperExtensions.WebServerSectionName);
            }
            else
            {
                webServerElement = XElement.Parse(webServerSectionRawXml);
            }

            XElement handlersElement = webServerElement.Element("handlers");

            if (handlersElement == null)
            {
                handlersElement = new XElement("handlers");
                webServerElement.Add(handlersElement);
            }

            XElement addElement = handlersElement.Elements("add")
                .FirstOrDefault(e =>
                {
                    XAttribute attr = e.Attribute("type");
                    return attr != null && attr.Value == fullTypeName;
                });

            if (addElement == null)
            {
                addElement = new XElement("add",
                   new XAttribute("name", name),
                   new XAttribute("verb", "GET"),
                   new XAttribute("path", redirectHandlerPath),
                   new XAttribute("type", fullTypeName));
                handlersElement.Add(addElement);
            }

            webServerSection.SectionInformation.SetRawXml(webServerElement.ToString());
        }
        /// <summary>
        /// Retrieves or creates the system.webServer section
        /// </summary>
        /// <remarks>
        /// This section self initializes to empty xml, so if we detect that condition,
        /// we initialize it to empty but valid xml so that it can be manipulated.
        /// </remarks>
        /// <returns>The existing or new system.webServer section.</returns>
        public IgnoreSection GetOrCreateSystemWebServerSection()
        {
            // This section has no strongly typed equivalent, so we treat it only as an IgnoreSection
            IgnoreSection webServerSection = this._configuration.GetSection(SystemWebServerSectionName) as IgnoreSection;
            if (webServerSection == null)
            {
                webServerSection = new IgnoreSection();
                this._configuration.Sections.Add(SystemWebServerSectionName, webServerSection);
            }

            // Detect empty xml and initialize it to legal empty state if found.
            // We do this to simplify the logic of parsing it and adding new sections.
            SectionInformation sectionInformation = webServerSection.SectionInformation;
            string rawXml = sectionInformation.GetRawXml();
            if (string.IsNullOrEmpty(rawXml))
            {
                rawXml = "<" + SystemWebServerSectionName + "/>";
                sectionInformation.SetRawXml(rawXml);
            }
            return webServerSection;
        }