Fix a test case failing to build.
diff --git a/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestableLinkStorageImpl.java b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestableLinkStorageImpl.java
index 223b8a1..5709f03 100644
--- a/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestableLinkStorageImpl.java
+++ b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestableLinkStorageImpl.java
@@ -17,6 +17,7 @@
  */
 
 public class TestableLinkStorageImpl extends LinkStorageImpl {
+	protected TitanGraph graph;
 
 	public TestableLinkStorageImpl(TitanGraph graph){
 		this.graph = graph;