* Added JsonSerialize to the Flow-related containers.
* Implement the remaining toString() methods that were
  returning empty strings.
diff --git a/src/main/java/net/floodlightcontroller/util/CallerId.java b/src/main/java/net/floodlightcontroller/util/CallerId.java
index 898da31..200b9e0 100644
--- a/src/main/java/net/floodlightcontroller/util/CallerId.java
+++ b/src/main/java/net/floodlightcontroller/util/CallerId.java
@@ -1,8 +1,14 @@
 package net.floodlightcontroller.util;
 
+import net.floodlightcontroller.util.serializers.CallerIdSerializer;
+
+import org.codehaus.jackson.annotate.JsonProperty;
+import org.codehaus.jackson.map.annotate.JsonSerialize;
+
 /**
  * The class representing a Caller ID for an ONOS component.
  */
+@JsonSerialize(using=CallerIdSerializer.class)
 public class CallerId {
     private String value;