WP_REST_Revisions_Controller::prepare_date_response PHP Method

    protected function prepare_date_response($date_gmt, $date = null)
    {
        if ('0000-00-00 00:00:00' === $date_gmt) {
            return null;
        }
        if (isset($date)) {
            return mysql_to_rfc3339($date);
        }
        return mysql_to_rfc3339($date_gmt);
    }