Piwik\Widget\WidgetContainerConfig::addWidgetConfig PHP Method

    public function addWidgetConfig(WidgetConfig $widget)
    {
        $this->widgets[] = $widget;
        return $this;
    }

 private function addContainer(WidgetContainerConfig $containerWidget)
 {
     $widgetId = $containerWidget->getId();
     $this->container[$widgetId] = $containerWidget;
     // widgets were added to this container, but the container did not exist yet.
     if (isset($this->containerWidgets[$widgetId])) {
         foreach ($this->containerWidgets[$widgetId] as $widget) {
             $containerWidget->addWidgetConfig($widget);
         }
         unset($this->containerWidgets[$widgetId]);
     }
 }