Add new API for Image Carousel

[nnsnodnb]

https://devdocs.line.me/en/#image-carousel

[okdtsk]

Thank you for your contribution!

The action field of image carousel template is not list but just json object unlike CarouselTemplate.
ref) https://devdocs.line.me/en/#template-messages

Could you fix your implementation of ImageCarouselColumn and its test?

• Example json item of columns for image carousel template

{
    "imageUrl": "https://example.com/bot/images/item1.jpg",
    "action": {
    "type": "postback",
    "label": "Buy",
    "data": "action=buy&itemid=111"
  }
}

[nnsnodnb]

Oh, sorry ;(
It is being revised now.

[okdtsk]

Thanks for your updates!

I suggest not to separate postback action for standard templates and for image carousel because there is no difference except for the length of label value and our implementation has no validation process to check its length so we can use existing PostbackTemplateAction for image carousel.
Additionally it is better that each action/event has single corresponding class to reduce future maintenance cost of this sdk IMO.

https://devdocs.line.me/en/#template-message

Instead of new implementation of postback action for image carousel, how about modify docstring of existing ***TemplateAction?

[bheghenkz]

bisa tolong buatkan saya bot. anti kicker

[nnsnodnb]

@okdtsk
Sorry...
I fixed it to implementation in PostbackTemplateAction .
I actually implemented it in the application and confirmed the expected behavior.
Remove ImagePostbackTemplateAction .

[okdtsk]

@nnsnodnb
Thank you, LGTM I'll merge this pr.

@bheghenkz
If you have a general question of line bot, please ask in https://github.com/line/line-bot-faq. That repository is for general usage of line bot and separate from each sdk repo due to separation of concerns.