[ONOS-7279] Fix for illegal state exception when deactivating driver providers

Change-Id: I9a8c16e33cac40b91c2b6f405e66f94bcdf5e0e0
diff --git a/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java b/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
index 9b82f5f..c78108c 100644
--- a/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
+++ b/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
@@ -120,6 +120,7 @@
 
     @Deactivate
     public void deactivate() {
+        defaultProvider.terminate();
         deviceService.removeListener(deviceListener);
         cfgService.unregisterProperties(getClass(), false);
         store.unsetDelegate(delegate);