onos-6309:avoiding null pointer exception in public method for body object

Change-Id: I883969ef7f8da9675d24ebb01fb53e0c120c58f7
diff --git a/apps/rabbitmq/src/main/java/org/onosproject/rabbitmq/impl/MQServiceImpl.java b/apps/rabbitmq/src/main/java/org/onosproject/rabbitmq/impl/MQServiceImpl.java
index db02806..2a2f617 100644
--- a/apps/rabbitmq/src/main/java/org/onosproject/rabbitmq/impl/MQServiceImpl.java
+++ b/apps/rabbitmq/src/main/java/org/onosproject/rabbitmq/impl/MQServiceImpl.java
@@ -128,6 +128,7 @@
             body = bytesOf(MQUtil.json((LinkEvent) event));
         } else {
             log.error("Invalid event: '{}'", event);
+            return;
         }
         processAndPublishMessage(body);
     }