oauth refresh method is sync

[feniljain]

Hey team! 👋🏻

I was trying to use SASL OAUTHBEARER for authentication with rust-rdkafka, I found I would have to implement ClientContext with ENABLE_REFRESH_OAUTH_TOKEN true and generate_oauth_token specifically to refresh the token. AWS provides libraries in different languages to generate this token, a few are listed here.

I found this library, aws-msk-iam-sasl-signer that does the same for rust, but it seems generate_oauth_token is a sync method and generate_auth_token method provided by the library is async.

I am raising an issue to understand a point in general, these oauth token generation would almost always be async in general, would it make sense to make changes to make it an async function in trait? Or am I missing something?