Method enqueueMessage

/**
 * Enqueue a system message.
 *
 * @param   string  $msg   The message to enqueue.
 * @param   string  $type  The message type.
 *
 * @return  void
 *
 * @since   4.0.0
 */
public function enqueueMessage($msg, $type = self::MSG_INFO)
{
    if (!\array_key_exists($type, $this->messages)) {
        $this->messages[$type] = [];
    }
    $this->messages[$type][] = $msg;
}