onUnsubscription method
Event handler called when an MpnSubscription has been successfully unsubscribed from on the server's MPN Module.
After this call no more events can be received until a new onSubscription event.
Note that this event can be called multiple times in the life of an MpnSubscription instance only in case it is subscribed multiple times
through LightstreamerClient.unsubscribeMpn and LightstreamerClient.subscribeMpn. Two consecutive calls
to this method are not possible, as before a second onUnsubscription event an onSubscription event is always fired.
Implementation
void onUnsubscription() {}