Add Kafka integration for DHCP L2 relay app

Change-Id: Ieda0784ca2cc7ba3898cb734f3ff8f2c754bb3fb
diff --git a/src/main/java/org/opencord/kafka/integrations/AaaKafkaIntegration.java b/src/main/java/org/opencord/kafka/integrations/AaaKafkaIntegration.java
index 471792f..e68e307 100644
--- a/src/main/java/org/opencord/kafka/integrations/AaaKafkaIntegration.java
+++ b/src/main/java/org/opencord/kafka/integrations/AaaKafkaIntegration.java
@@ -31,6 +31,8 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.time.Instant;
+
 /**
  * Listens for AAA events and pushes them on a Kafka bus.
  */
@@ -49,6 +51,7 @@
 
     private static final String TOPIC = "authentication.events";
 
+    private static final String TIMESTAMP = "timestamp";
     private static final String DEVICE_ID = "deviceId";
     private static final String PORT_NUMBER = "portNumber";
     private static final String AUTHENTICATION_STATE = "authenticationState";
@@ -72,6 +75,7 @@
     private JsonNode serialize(AuthenticationEvent event) {
         ObjectMapper mapper = new ObjectMapper();
         ObjectNode authEvent = mapper.createObjectNode();
+        authEvent.put(TIMESTAMP, Instant.now().toString());
         authEvent.put(DEVICE_ID, event.subject().deviceId().toString());
         authEvent.put(PORT_NUMBER, event.subject().port().toString());
         authEvent.put(AUTHENTICATION_STATE, event.type().toString());