# Functions
NewXoauth2Client provides an implementation of the XOAUTH2 authentication mechanism, as described in https://developers.google.com/gmail/xoauth2_protocol and https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#sasl-xoauth2
NOTE: The required base64 encoding of the XOAUTH2 string is performed by the emersion/go-imap library as part of submitting the AUTHENTICATE command.
# Constants
Xoauth2 is the IMAP authentication mechanism name.
# Structs
Xoauth2Error represents an error encountered during an XOAUTH2 authentication attempt.
# Interfaces
Client interface to perform challenge-response authentication.