Change scope to protected

Change-Id: I92b70970b8fa3d89856932ffdff5e9fb744b15d5
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
index 361c298..4d060de 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
@@ -11,8 +11,8 @@
  *
  */
 public class LinkEvent {
-    private final SwitchPort src;
-    private final SwitchPort dst;
+    protected final SwitchPort src;
+    protected final SwitchPort dst;
 
     /**
      * Default constructor.