How to use nextcloud 24 new improvements search API

According to the issued nextcloud24 notice, a new search API is found(Nextcloud Hub 24 is here - Nextcloud), How to use this API ?
Where are the relevant codes?
Is there an instruction manual?

Good question. Tried searching the server repo issues and prs, but didn’t find any details. Announcement is:

Enterprise search API. The new API allows content on Nextcloud to be indexed by a third-party search tool.