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

Change-Id: Ie41271fa02740560bd67b0faf49f633ee749773c
diff --git a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
index d5b12b3..b92067f 100644
--- a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
@@ -498,10 +498,10 @@
                 FlowRuleBatchOperation batchOperation =
                         request.asBatchOperation(deviceId);
 
-                FlowRuleProvider flowRuleProvider =
-                        getProvider(deviceId);
-
-                flowRuleProvider.executeBatch(batchOperation);
+                FlowRuleProvider flowRuleProvider = getProvider(deviceId);
+                if (flowRuleProvider != null) {
+                    flowRuleProvider.executeBatch(batchOperation);
+                }
 
                 break;