Add facade object called UnifiedDiscreteResources

This is for ONOS-4281

Change-Id: I04649932fdb8983492878732a04c93a21b4cafe7
(cherry picked from commit ac6ff6e1984e0351938467be7677072888258c7d)
diff --git a/core/store/dist/src/main/java/org/onosproject/store/resource/impl/TransactionalDiscreteResourceSubStore.java b/core/store/dist/src/main/java/org/onosproject/store/resource/impl/TransactionalDiscreteResourceSubStore.java
index 2803a3c..d4306a7 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/resource/impl/TransactionalDiscreteResourceSubStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/resource/impl/TransactionalDiscreteResourceSubStore.java
@@ -59,7 +59,7 @@
             return true;
         }
 
-        DiscreteResources requested = new NonEncodableDiscreteResources(values);
+        DiscreteResources requested = DiscreteResources.of(values);
         DiscreteResources oldValues = childMap.putIfAbsent(key, requested);
         if (oldValues == null) {
             return true;