[ONOS-3253/3144] Insert support for Netconf device configuration, set and get controllers commands

Change-Id: I99188aa18207b9d0b0d935b9f9e61e547f4ddab1
diff --git a/cli/src/main/java/org/onosproject/cli/net/DeviceSetControllersCommand.java b/cli/src/main/java/org/onosproject/cli/net/DeviceSetControllersCommand.java
index c369379..cb4ff04 100644
--- a/cli/src/main/java/org/onosproject/cli/net/DeviceSetControllersCommand.java
+++ b/cli/src/main/java/org/onosproject/cli/net/DeviceSetControllersCommand.java
@@ -59,8 +59,11 @@
         ControllerConfig config = h.behaviour(ControllerConfig.class);
         print("before:");
         config.getControllers().forEach(c -> print(c.target()));
-
-        config.setControllers(newControllers);
+        try {
+            config.setControllers(newControllers);
+        } catch (NullPointerException e) {
+            print("No Device with requested parameters {} ", uri);
+        }
         print("after:");
         config.getControllers().forEach(c -> print(c.target()));
         print("size %d", config.getControllers().size());