Fix for Kryo related issue crossing OSGi bundle boundaries.

Change-Id: I121dfe360de14a5b4760e5d2fd8cb2db93e0be63
diff --git a/core/net/src/test/java/org/onlab/onos/net/device/impl/DistributedDeviceManagerTest.java b/core/net/src/test/java/org/onlab/onos/net/device/impl/DistributedDeviceManagerTest.java
index a928572..222216c 100644
--- a/core/net/src/test/java/org/onlab/onos/net/device/impl/DistributedDeviceManagerTest.java
+++ b/core/net/src/test/java/org/onlab/onos/net/device/impl/DistributedDeviceManagerTest.java
@@ -112,7 +112,7 @@
         mgr.deactivate();
 
         dstore.deactivate();
-        dstore.theInstance.shutdown();
+        ((TestDistributedDeviceStore) dstore).shutdownHz();
     }
 
     private void connectDevice(DeviceId deviceId, String swVersion) {
@@ -290,5 +290,12 @@
                 }
             };
         }
+
+        /**
+         * Shutdowns the hazelcast instance.
+         */
+        public void shutdownHz() {
+            theInstance.shutdown();
+        }
     }
 }