What plugin control html_attributes? The html.html.twig template contains the following line.

&lt;html{{ html_attributes }}&gt;


On my site, it outputs the following markup.

&lt;html lang="ru" dir="ltr" xmlns:article="http://ogp.me/ns/article#" xmlns:book="http://ogp.me/ns/book#" xmlns:product="http://ogp.me/ns/product#" xmlns:profile="http://ogp.me/ns/profile#" xmlns:video="http://ogp.me/ns/video#" prefix="content: http://purl.org/rss/1.0/modules/content/  dc: http://purl.org/dc/terms/  foaf: http://xmlns.com/foaf/0.1/  og: http://ogp.me/ns#  rdfs: http://www.w3.org/2000/01/rdf-schema#  schema: http://schema.org/  sioc: http://rdfs.org/sioc/ns#  sioct: http://rdfs.org/sioc/types#  skos: http://www.w3.org/2004/02/skos/core#  xsd: http://www.w3.org/2001/XMLSchema# "&gt;


What plugin or core function controls it?
They're added in template_preprocess_html:

$variables['html_attributes'] = new Attribute();


To alter them, you can implement hook_preprocess_html in your theme or module.