Access token response
(Optional) Best approximation available of the token generation time. May be used in token expiration time calculations. Clock.currTime is used if timestamp is omitted or set to SysTime.init.
true if this is called in the process of loading a persisted session. If this is true, timestamp is required.
OAuthException if:
Handles the response to an access token request and sets the properties of this session accordingly.
This method is to be overridden by derived classes to implement support for additional token types and/or extension fields in the response.
The default implementation only supports the the 'bearer' token type and the response fields documented in RFC 6749 sections 5.1 and 5.2.