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

Change-Id: I1e7e0d62e27012cd090f3a72eb92eadc85afafdf
(cherry picked from commit 5c7fe3acf43bf1304038a7be55a5fd45e5805396)
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 ac97636..9dc92d1 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
@@ -295,6 +295,13 @@
     }
 
     @Override
+    public FlowEntry getFlowEntry(FlowRule rule) {
+        checkPermission(FLOWRULE_READ);
+        checkNotNull(rule, FLOW_RULE_NULL);
+        return store.getFlowEntry(rule);
+    }
+
+    @Override
     public Iterable<FlowEntry> getFlowEntries(DeviceId deviceId) {
         checkPermission(FLOWRULE_READ);
         checkNotNull(deviceId, DEVICE_ID_NULL);