wp-includes/rest-api/class-wp-rest-request.php:283Sets headers on the request.
$headersarray$overridebooloptionaltrue public function set_headers( $headers, $override = true ) { if ( true === $override ) { $this->headers = array(); } foreach ( $headers as $key => $value ) { $this->set_header( $key, $value ); } }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-request.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.