Customsing the Sitecore HTML cache clearer

HtmlCacheClearer.config

<settings>
      <!--
        A pipe separated list of content ID's. When a publish occurs if the item 
        being published is one of these items,
        or a child of one of these items then the HTML cache isn't cleared.
      -->
      <setting name="CustomHtmlCacheClearer.IgnoreItems" value="/sitecore/content"/>
    </settings>

    <events>
      <event name="publish:end">
        <handler type="Sitecore.Publishing.HtmlCacheClearer, Sitecore.Kernel" method="ClearCache">
          <patch:delete />
        </handler>
        <handler type="CustomHtmlCacheClearer.HtmlCacheClearer, CustomHtmlCacheClearer" method="ClearCache">
          <sites hint="list">
            <site>website</site>
          </sites>
        </handler>
      </event>
      <event name="publish:end:remote">
        <handler type="Sitecore.Publishing.HtmlCacheClearer, Sitecore.Kernel" method="ClearCache">
          <patch:delete />
        </handler>
        <handler type="CustomHtmlCacheClearer.HtmlCacheClearer, CustomHtmlCacheClearer" method="ClearCache">
          <sites hint="list">
            <site>website</site>
          </sites>
        </handler>
      </event>
      <event name="indexing:end">
        <handler type="CustomHtmlCacheClearer.IndexCacheClearer, CustomHtmlCacheClearer" method="Clear"/>
      </event>
    </events>

HtmlCacheClearer.cs

public class HtmlCacheClearer : Sitecore.Publishing.HtmlCacheClearer
    {
        private const string SettingName = "CustomHtmlCacheClearer.IgnoreItems";

        public new void ClearCache(object sender, EventArgs args)
        {
            if (sender == null)
            {
                return;
            }

            var sitecoreEventArgs = args as SitecoreEventArgs;
            if (sitecoreEventArgs == null || !sitecoreEventArgs.Parameters.Any())
            {
                return;
            }

            var publisher = sitecoreEventArgs.Parameters[0] as Publisher;
            if (publisher == null)
            {
                return;
            }

            if (IsCacheClearRequired(publisher.Options))
            {
                base.ClearCache(sender, args);
            }
        }

        protected bool IsCacheClearRequired(PublishOptions publishOptions)
        {
            var exemptPaths = Sitecore.Configuration.Settings.GetSetting(SettingName);
            if (string.IsNullOrWhiteSpace(exemptPaths))
            {
                return true;
            }

            return exemptPaths.Split('|')
                              .All(excemptPath => !publishOptions.RootItem.Paths.FullPath.StartsWith(excemptPath,StringComparison.OrdinalIgnoreCase));
        }
    }