Add node IP attribute in k8s node class with minor code refactoring

Change-Id: I4c1c86c95acfeb38569b91c1677e4ce8af90460f
diff --git a/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sNode.java b/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sNode.java
index 6631e55..eabb13a 100644
--- a/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sNode.java
+++ b/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sNode.java
@@ -187,6 +187,13 @@
     IpAddress dataIp();
 
     /**
+     * Returns the kubernetes node IP address.
+     *
+     * @return ip address; null if node has no IP address
+     */
+    IpAddress nodeIp();
+
+    /**
      * Returns the initialization state of the node.
      *
      * @return node state
@@ -647,6 +654,14 @@
         Builder dataIp(IpAddress dataIp);
 
         /**
+         * Returns the kubernetes node builder with supplied node IP address.
+         *
+         * @param nodeIp node IP address
+         * @return kubernetes node builder
+         */
+        Builder nodeIp(IpAddress nodeIp);
+
+        /**
          * Returns kubernetes node builder with supplied node state.
          *
          * @param state kubernetes node state