Fix a bug that appeared because of the stale Titan vertices workaround fix.
diff --git a/src/main/java/net/floodlightcontroller/flowcache/FlowManager.java b/src/main/java/net/floodlightcontroller/flowcache/FlowManager.java
index beb8bd0..2893c1d 100644
--- a/src/main/java/net/floodlightcontroller/flowcache/FlowManager.java
+++ b/src/main/java/net/floodlightcontroller/flowcache/FlowManager.java
@@ -1185,7 +1185,8 @@
 	    // Extract the Flow state
 	    //
 	    FlowPath flowPath = extractFlowPath(flowObj);
-	    flowPaths.add(flowPath);
+	    if (flowPath != null)
+		flowPaths.add(flowPath);
 	}
 
 	conn.endTx(Transaction.COMMIT);