Connection credentials expiration (JWT)

- [ no] Bug exists Release Version 1.2.5 ( Master Branch)
- [ no] Bug exists in MQTTv3 Client on Snapshot Version 1.2.6-SNAPSHOT (Develop Branch)
- [ no] Bug exists in MQTTv5 Client on Snapshot Version 1.2.6-SNAPSHOT (Develop Branch)

We are using the `MqttClient` v mqttv3 1.2.2. We have the same issue as described in https://github.com/eclipse/paho.mqtt.c/issues/808. How do we solve it in the java client? Should we do the same as the suggestion in https://github.com/eclipse/paho.mqtt.c/issues/808#issuecomment-622668215, and if so could you please provide more details how exactly that is done?

Otherwise, could we rely on the built-in auto-reconnection and override the `MqttConnectOptions.getPassword()` to provide a (potentionally new) valid token whenever called? Looking at the code of the client, this seems like it should work, but then it is not officially documented, that the built-in auto-reconnect always uses the connect options(instead of for example caching the settings in an entirely different object).