Allows redirected posts in the sitemap feed if they are explicitly allowed via the externalPostAllowedInSitemap post property. Normally we don’t want to do this, because the sitemap can’t link to other domains, not even subdomains, unless the other domain is verified in the Google Search Console.

https://interactives.theroot.com/root-100-2018/

When a new interactive is created it will need to be added to Google Search Console and added to it’s parent site’s sitemap.