Unit tests for the flow objective store

Change-Id: I6223d973bba5e680396c338a3d8d0663a028d02b
diff --git a/core/api/src/test/java/org/onosproject/store/service/TestStorageService.java b/core/api/src/test/java/org/onosproject/store/service/TestStorageService.java
index 4901cfa..9b52a30 100644
--- a/core/api/src/test/java/org/onosproject/store/service/TestStorageService.java
+++ b/core/api/src/test/java/org/onosproject/store/service/TestStorageService.java
@@ -40,7 +40,7 @@
 
     @Override
     public AtomicCounterBuilder atomicCounterBuilder() {
-        throw new UnsupportedOperationException("atomicCounterBuilder");
+        return TestAtomicCounter.builder();
     }
 
     @Override