SharePoint - Search : How to Get the Content Source ID programatically

private Guid FetchContentSourceID(SPSite site, string contentSourceName)
{
    var serviceContext = SPServiceContext.GetContext(site);
    var proxy = (SearchServiceApplicationProxy)serviceContext.GetDefaultProxy(typeof(SearchServiceApplicationProxy));
    var federationManager = new FederationManager(proxy);
    var searchObjectOwner = new SearchObjectOwner(SearchObjectLevel.SPWeb, site.RootWeb);
    var searchObjectFilter = new SearchObjectFilter(searchObjectOwner) { IncludeHigherLevel = true };
    var contentSources = federationManager.ListSources(searchObjectFilter , false);
    var contentSource = (from source in contentSources
                       where source.Name == contentSourceName
                       select source).FirstOrDefault();
    if (contentSource != null)
    {
        return contentSource .Id;
    }
    else
    {
        return Guid.Empty;
    }
}