public function addCategory(ChildCategory $l)
    {
        if ($this->collCategories === null) {
            $this->initCategories();
            $this->collCategoriesPartial = true;
        }

        if (!$this->collCategories->contains($l)) {
            $this->doAddCategory($l);

            if ($this->categoriesScheduledForDeletion and $this->categoriesScheduledForDeletion->contains($l)) {
                $this->categoriesScheduledForDeletion->remove($this->categoriesScheduledForDeletion->search($l));
            }
        }

        return $this;
    }