Handle exception in java client when token is expired

[visit24ir]

Is there a clear way to handle exceptions when jwt token is expired ?

In javascript client such as mqtt.js , when i send expired token to password field in connect method, offline method is called.In Java though, there is a package called: Eclipse Paho 'connectionLost' event is called.here is the thing :

By and large, there is not an appropriate way to handle token expiration exception in clients.
connection lost event could occure everywhere and every time, not just in token expiration
for instance : when mqtt server is offline or when s.th happend to connection. so there is not a transparent way to handle this.
1. What happens in backend side when an expired token is sent in password field ?
2. What event should be called in client side ?
3. How do detect in clients that emqx server denies the connection because there is an expired jwt token ?