Piwik\Config::getInstance PHP Method

    public static function getInstance()
    {
        return StaticContainer::get('Piwik\\Config');
    }

 public static function update()
 {
     $salt = Common::generateUniqId();
     $config = Config::getInstance();
     $superuser = $config->superuser;
     if (!isset($superuser['salt'])) {
         try {
             if (is_writable(Config::getLocalConfigPath())) {
                 $superuser['salt'] = $salt;
                 $config->superuser = $superuser;
                 $config->forceSave();
             } else {
                 throw new \Exception('mandatory update failed');
             }
         } catch (\Exception $e) {
             throw new \Piwik\UpdaterErrorException("Please edit your config/config.ini.php file and add below <code>[superuser]</code> the following line: <br /><code>salt = {$salt}</code>");
         }
     }
     $plugins = $config->Plugins;
     if (!in_array('MultiSites', $plugins)) {
         try {
             if (is_writable(Config::getLocalConfigPath())) {
                 $plugins[] = 'MultiSites';
                 $config->Plugins = $plugins;
                 $config->forceSave();
             } else {
                 throw new \Exception('optional update failed');
             }
         } catch (\Exception $e) {
             throw new \Exception("You can now enable the new MultiSites plugin in the Plugins screen in the Piwik admin!");
         }
     }
     Updater::updateDatabase(__FILE__, self::getSql());
 }