Google\Cloud\Logger\AppEngineFlexFormatter::format PHP Method

    public function format(array $record)
    {
        $message = parent::format($record);
        list($usec, $sec) = explode(" ", microtime());
        $usec = (int) ((double) $usec * 1000000000);
        $sec = (int) $sec;
        $payload = ['message' => $message, 'timestamp' => ['seconds' => $sec, 'nanos' => $usec], 'thread' => '', 'severity' => $record['level_name']];
        if (isset($_SERVER['HTTP_X_CLOUD_TRACE_CONTEXT'])) {
            $payload['traceId'] = explode("/", $_SERVER['HTTP_X_CLOUD_TRACE_CONTEXT'])[0];
        }
        return "\n" . json_encode($payload);
    }