How to create Language Associations using Joomla API

[MayaSima]

Hi Everyone,

I am publishing some articles in different languages for a multilingual site and need to link them after they are published.
I see there is a field for that:

"languageAssociations": { "data": [ { "type": "articles", "id": "8702" },...]

But when I am trying to send a PATCH request with the payload that looks like this:

{"languageAssociations": ["8888", "9999"]}

it fails with some random error that required fields are missing (which have never been required in other PATCH requests I make)
I suspect something else is going on. I also tried to replace "languageAssociations" with "association", but it didn't help.

The relevant documentation links are dead (found them through search engine): https://docs.joomla.org/Help310:Content_Language_Associations, https://api.joomla.org/cms-3/classes/Joomla.CMS.Router.ContentHelperRoute.html

Any help much appreciated!