Improve test coverage for DefaultDeviceDescription

Change-Id: If779ceb26f390fbe6e3ec4302a4c9cb054a21fe2
diff --git a/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceDescription.java b/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceDescription.java
index 91ce5af..0a4c705 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceDescription.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceDescription.java
@@ -206,7 +206,7 @@
     }
 
     // default constructor for serialization
-    private DefaultDeviceDescription() {
+    DefaultDeviceDescription() {
         this.uri = null;
         this.type = null;
         this.manufacturer = null;