tokenPrivilegeWillExpire property Null safety
Occurs when the token expires in 30 seconds.
The user becomes offline if the token used when joining the channel expires. This callback is triggered 30 seconds before the token expires, to remind the app to get a new token. Upon receiving this callback, you need to generate a new token on the server and call RtcChannel.renewToken to pass the new token to the SDK.
TokenCallback typedef includes the following parameters:
token: The token that will expire in 30 seconds.