Fix: add a REST API to update K8S node state to post-on-board

Change-Id: Ia10092a539cbe12d206951f30cc1c3d6debc3860
diff --git a/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/web/K8sNodeWebResource.java b/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/web/K8sNodeWebResource.java
index 2f12f25..042e932 100644
--- a/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/web/K8sNodeWebResource.java
+++ b/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/web/K8sNodeWebResource.java
@@ -262,7 +262,11 @@
     @Produces(MediaType.APPLICATION_JSON)
     @Path("update/postonboard/{hostname}")
     public Response postOnBoardNode(@PathParam("hostname") String hostname) {
-        nodeAdminService.node(hostname).updateState(POST_ON_BOARD);
+        K8sNode node = nodeAdminService.node(hostname);
+        if (node != null && node.state() != POST_ON_BOARD) {
+            K8sNode updated = node.updateState(POST_ON_BOARD);
+            nodeAdminService.updateNode(updated);
+        }
         return Response.ok().build();
     }