I am working on a web app which will need to implement the three-legged OAuth 2.0 flow. The Smartsheet API docs http://smartsheet.com/developers/api-documentation say that the API supports standard OAuth 2.0 flow. On closer inspection, however, I see that access and refresh token management operations require that instead of sending over the client secret (which appears to be the standard behavior in other APIs), I have to send over a hash, quoting "SHA-256 hash of your client secret concatenated with a pipe and the authorization code. The client_secret is never sent with the request."
Given that this is different from the standard OAuth 2.0 flow, does Smartsheet API support the standard behavior?