onSubscription method
Event handler called when an MpnSubscription has been successfully subscribed to on the server's MPN Module.
This event handler is always called before other events related to the same subscription.
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 onSubscription()
event an onUnsubscription event is always fired.
Implementation
void onSubscription() {}