Allow cordvtn to work without XOS for now

Change-Id: I6c9bb199879ecdb0b68538475135cac424136ab3
diff --git a/src/main/java/org/onosproject/cordvtn/impl/CordVtn.java b/src/main/java/org/onosproject/cordvtn/impl/CordVtn.java
index 0a7b77d..f816cf9 100644
--- a/src/main/java/org/onosproject/cordvtn/impl/CordVtn.java
+++ b/src/main/java/org/onosproject/cordvtn/impl/CordVtn.java
@@ -779,7 +779,10 @@
      * @param xosAccess xos access
      */
     private void setXosAccess(XosAccess xosAccess) {
-        checkNotNull(xosAccess, "XOS access is not configured");
+        if (xosAccess == null) {
+            log.warn("XOS access is not configured");
+            return;
+        }
 
         log.debug("Set XOS access with Endpoint: {} User: {} Passwd: {}",
                   xosAccess.endpoint(),