Illuminate\Routing\Router::getGroupStack PHP Method

    public function getGroupStack()
    {
        return $this->groupStack;
    }

 /**
  * Parse a string based action for the "uses" fluent method.
  *
  * @param  string  $action
  * @return string
  */
 protected function addGroupNamespaceToStringUses($action)
 {
     $groupStack = last($this->router->getGroupStack());
     if (isset($groupStack['namespace']) && strpos($action, '\\') !== 0) {
         return $groupStack['namespace'] . '\\' . $action;
     }
     return $action;
 }