Confusing or incomplete API Documentation

When using the nylas Confirm Booking Api as documented here
the Salt in the request body is described as follows:

The salt extracted from the booking reference embedded in the organizer confirmation link, encoded as a URL-safe base64 string (without padding).

how ever there is no explanation on how to extract the salt from the booking reference! we have experimented with multiple different approaches and have searched the documentaion throughly with no luck!

@ram there is also a similar question here that is unanswered.

Please advise as where and how we can get the Salt needed for this API.