ONOS-2145  Added ability to withdraw packet intercepts via PacketService::cancelPackets.

Change-Id: Ie41271fa02740560bd67b0faf49f633ee749773c
diff --git a/core/common/src/test/java/org/onosproject/store/trivial/SimplePacketStore.java b/core/common/src/test/java/org/onosproject/store/trivial/SimplePacketStore.java
index 81cef49..4345aba 100644
--- a/core/common/src/test/java/org/onosproject/store/trivial/SimplePacketStore.java
+++ b/core/common/src/test/java/org/onosproject/store/trivial/SimplePacketStore.java
@@ -52,6 +52,11 @@
     }
 
     @Override
+    public boolean cancelPackets(PacketRequest request) {
+        return requests.remove(request);
+    }
+
+    @Override
     public Set<PacketRequest> existingRequests() {
         return Collections.unmodifiableSet(requests);
     }