getAfterCategoryId example

protected $children;

    /** * @param TreeItem[] $children */
    public function __construct(
        ?CategoryEntity $category,
        array $children
    ) {
        $this->category = $category;
        $this->children = $children;
        $this->afterId = $category ? $category->getAfterCategoryId() : null;
    }

    public function getId(): string
    {
        return $this->getCategory()->getId();
    }

    public function setCategory(CategoryEntity $category): void
    {
        $this->category = $category;
        $this->afterId = $category->getAfterCategoryId();
    }