wp-includes/rest-api/class-wp-rest-response.php:203Sets the handler that was responsible for generating the response.
$handlerarray public function set_matched_handler( $handler ) { $this->matched_handler = $handler; }Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/class-wp-rest-response.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.