Flip before returning ByteBuffer

Change-Id: I7350e24f20d5686a8c6c43291d963070fe7da792
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
index 5aa7008..84b9360 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
@@ -37,7 +37,7 @@
 	if (dpid == null) {
 	    throw new IllegalArgumentException("dpid cannot be null");
 	}
-	return ByteBuffer.allocate(SwitchEvent.SWITCHID_BYTES).putChar('S').putLong(dpid);
+	return (ByteBuffer) ByteBuffer.allocate(SwitchEvent.SWITCHID_BYTES).putChar('S').putLong(dpid).flip();
     }
 
     public byte[] getID() {