To maintain compatibility with previous versions, I have made the following commit. This allows methods from previous versions to be used without modification, while still displaying the warning message.
c8b141c

validate_signature method should be implemented in the latest version.

I guess, generated codes in lib/clients/webhook doesn't support deserializing webhook's payload.
req = LINE::Client::Webhook::CalbackRequest.new(JSON.parse(request_body)) won't parse Hash object to nested object.
I mean, req is instance of LINE::Client::Webhook::CalbackRequest. But req.events[0] is just Hash, not an instance of the LINE::Client::Webhook::Event.

It's suprising.

I added the following code:

• Example implementation (Echo Bot)
• Methods to verify signatures
• Methods to map event classes
• Test code
• Generating clients from the latest LINE OpenAPI

https://github.com/zenizh/line-bot-sdk-ruby/blob/openapi/lib/clients/channel-access-token/lib/line_client_channel_access_token/api/channel_access_token_api.rb#L237-L283

is bit strange.

This endpoint has two functionalities: 'Issue from channel ID and channel secret' and 'Issue from JWT assertion.'

For 'Issue from channel ID and channel secret,' you need to make the request with 'grant_type,' 'client_id,' and 'client_secret.'

For 'Issue from JWT assertion,' you need to make the request with 'grant_type,' 'client_assertion_type,' and 'client_assertion.'

The OpenAPI definition specifies that one of these requests is required: link to the OpenAPI definition.

However, in this PR, all the required parameters for both patterns are listed, and there are a few issues:

1. It's defined as [String] in the RDoc, which means nil cannot be passed.
2. Due to client-side validation like here, you are required to provide valid values for parameters even if you are not using them in one of the patterns."

This pull request will be submitted as a new pull request, so it is closed for now.