Implement listeners for ConsistentMultimap.

Change-Id: Ica07d444c18af8ba7a9bbb120623512def572a48
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DelegatingAsyncConsistentMultimap.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DelegatingAsyncConsistentMultimap.java
index 5bd37c5..3db4dce 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DelegatingAsyncConsistentMultimap.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/DelegatingAsyncConsistentMultimap.java
@@ -16,14 +16,17 @@
 
 package org.onosproject.store.primitives.impl;
 
+import com.google.common.collect.Multiset;
+import org.onosproject.store.service.AsyncConsistentMultimap;
+import org.onosproject.store.service.MultimapEventListener;
+import org.onosproject.store.service.Versioned;
+
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 
-import com.google.common.collect.Multiset;
-import org.onosproject.store.service.AsyncConsistentMultimap;
-import org.onosproject.store.service.Versioned;
+import java.util.concurrent.Executor;
 
 /**
  * {@code AsyncConsistentMultimap} that merely delegates control to
@@ -133,6 +136,16 @@
     }
 
     @Override
+    public CompletableFuture<Void> addListener(MultimapEventListener<K, V> listener, Executor executor) {
+        return delegateMap.addListener(listener, executor);
+    }
+
+    @Override
+    public CompletableFuture<Void> removeListener(MultimapEventListener<K, V> listener) {
+        return delegateMap.removeListener(listener);
+    }
+
+    @Override
     public CompletableFuture<Map<K, Collection<V>>> asMap() {
         return delegateMap.asMap();
     }