According to T86278, we need to implement sitelinks ad badges. For now, sitelinks would contain just the fact that the Entity has link on certain wiki.
Implementation description: https://www.mediawiki.org/wiki/Wikibase/Indexing/Data_Model#Representing_sitelinks_and_badges
Change 184839 had a related patch set uploaded (by Smalyshev):
T86331: implementation for sitelinks & badges
Can this be closed? Patch is merged.