Again fix for FELIX-3426 UPnP Plugin device tracking is error-prone https://issues.apache.org/jira/browse/FELIX-3426 Actually the size would never be 0, the reason is that the service that is 'beeing removed' is still in the tracker. So when the tracker size is 1, we should unregister the plugin.
felix/trunk/webconsole-plugins/upnp/src/main/java/org/apache/felix/webconsole/plugins/upnp/internal/Activator.java