stc work queue test improvements

Change-Id: I8b9335b0bbfdc8a447c5955bf3621962ff112cb2
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DefaultDistributedWorkQueue.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DefaultDistributedWorkQueue.java
index bdc9d31..d16c1b8 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DefaultDistributedWorkQueue.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DefaultDistributedWorkQueue.java
@@ -7,9 +7,9 @@
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
-import org.onosproject.store.service.WorkQueue;
 import org.onosproject.store.service.Serializer;
 import org.onosproject.store.service.Task;
+import org.onosproject.store.service.WorkQueue;
 import org.onosproject.store.service.WorkQueueStats;
 
 import com.google.common.collect.Collections2;
@@ -73,4 +73,9 @@
     public CompletableFuture<Void> stopProcessing() {
         return backingQueue.stopProcessing();
     }
+
+    @Override
+    public CompletableFuture<Void> destroy() {
+        return backingQueue.destroy();
+    }
 }