Piwik\Category\Category::setId PHP Method

    public function setId($id)
    {
        $this->id = $id;
        return $this;
    }

 /**
  * @return CategoryList
  */
 public static function get()
 {
     $list = new CategoryList();
     $categories = StaticContainer::get('Piwik\\Plugin\\Categories');
     foreach ($categories->getAllCategories() as $category) {
         $list->addCategory($category);
     }
     // move subcategories into categories
     foreach ($categories->getAllSubcategories() as $subcategory) {
         $categoryId = $subcategory->getCategoryId();
         if (!$categoryId) {
             continue;
         }
         if ($list->hasCategory($categoryId)) {
             $category = $list->getCategory($categoryId);
         } else {
             $category = new Category();
             $category->setId($categoryId);
             $list->addCategory($category);
         }
         $category->addSubcategory($subcategory);
     }
     return $list;
 }