Piwik\Plugin\Manager::getPluginsDirectory PHP Method

    public static function getPluginsDirectory()
    {
        return PIWIK_INCLUDE_PATH . '/plugins/';
    }

 private function addPluginConfigs(ContainerBuilder $builder)
 {
     $plugins = Manager::getInstance()->getActivatedPluginsFromConfig();
     foreach ($plugins as $plugin) {
         $baseDir = Manager::getPluginsDirectory() . $plugin;
         $file = $baseDir . '/config/config.php';
         if (file_exists($file)) {
             $builder->addDefinitions($file);
         }
         $environmentFile = $baseDir . '/config/' . $this->environment . '.php';
         if (file_exists($environmentFile)) {
             $builder->addDefinitions($environmentFile);
         }
     }
 }