Fix to reinstall flow rules when they are missing in FlowRuleService.

Change-Id: I1e7e0d62e27012cd090f3a72eb92eadc85afafdf
(cherry picked from commit 5c7fe3acf43bf1304038a7be55a5fd45e5805396)
diff --git a/core/api/src/test/java/org/onosproject/net/flow/FlowRuleServiceAdapter.java b/core/api/src/test/java/org/onosproject/net/flow/FlowRuleServiceAdapter.java
index 4f53b96..1ccbbc8 100644
--- a/core/api/src/test/java/org/onosproject/net/flow/FlowRuleServiceAdapter.java
+++ b/core/api/src/test/java/org/onosproject/net/flow/FlowRuleServiceAdapter.java
@@ -29,6 +29,11 @@
     }
 
     @Override
+    public FlowEntry getFlowEntry(FlowRule rule) {
+        return null;
+    }
+
+    @Override
     public Iterable<FlowEntry> getFlowEntries(DeviceId deviceId) {
         return null;
     }