src/Model/Article.php
public function attachGallery(Gallery $gallery): self
    {
        return $this->attach(
            self::ATTACHMENT_FIELD_GALLERY,
            $this->ensureOrder(
                $gallery,
                self::ATTACHMENT_FIELD_GALLERY
            )
        );
    }
public function attachGallery(Gallery $gallery): self
    {
        return $this->attach(
            self::ATTACHMENT_FIELD_GALLERY,
            $this->ensureOrder(
                $gallery,
                self::ATTACHMENT_FIELD_GALLERY
            )
        );
    }
Attach gallery here