The reading web team discovered that no one was maintaining the RelatedArticles [1] extension despite it being deployed on Wikivoyage, so we have taken the time to clean it up and get it ported to extension.json etc and give it some love... Whilst doing so, we noticed that it depends on a CustomData [2] extension which seems to be an early version of setExtensionData on ParserOutput. We removed this dependency, and we wondered if any other extensions is using CustomData. We'd be keen to undeploy it from the cluster if not. Anyone know about its history? There's a Flow discussion here if anyone wants to chip in: https://www.mediawiki.org/wiki/Topic:Sqcxzoee4lz8wxc3 [1] https://www.mediawiki.org/wiki/Extension:RelatedArticles [2] https://www.mediawiki.org/wiki/Extension:CustomData