wp-includes/class-wp-object-cache.php:558Clears the object cache of all data.
true public function flush() { $this->cache = array(); return true; }Introduced in 2.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-object-cache.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.