wp-includes/rest-api/endpoints/class-wp-rest-settings-controller.php:316Custom sanitize callback used for all options to allow the use of 'null'.
$valuemixed$requestWP_REST_Request$paramstringmixed|WP_Error public function sanitize_callback( $value, $request, $param ) { if ( is_null( $value ) ) { return $value; } return rest_parse_request_arg( $value, $request, $param ); }Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/endpoints/class-wp-rest-settings-controller.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.