- Variant's image should be one of related Product's image
- while update options, variants object are needed, and every single variant.option should match with options object.
- while all variant's image is empty, need_variant_image will automatically update to
- while variant's image is present, need_variant_image flag will update to
- while update variant's image, either using image object, or image_id is fine, but if both present, image_id will be used.
- while update/create metafield, system wouldn't delete metafield record existing.