Device is unregistered but still getting notification

Hi,

There is a common problem I saw around. Sometimes a device is registered multiple times. When you unregister it doesn't unregister all registrationIDs associated with the device. It just deletes one.

The scenario to recreate the issue is that if the user uninstalls our app, we won't be able to unregister their device. When they install again they will be registered twice. If we unregister latest registrationId, the first one still be in the hub.

Start by reproducing the repeated-registration and unregistration scenario in the Android SDK, then trace how registration IDs are stored and removed. Done means unregistering a device removes all registration IDs associated with it, so the unregistered device no longer receives notifications.

Written by the indexing model from the issue text.