correct a description of netconf exception,change the device name to user name

Change-Id: Idae12d26cc353f9a122940b7873bac13a76314d8
diff --git a/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfDeviceInfo.java b/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfDeviceInfo.java
index 4c900ea..a64dd54 100644
--- a/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfDeviceInfo.java
+++ b/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfDeviceInfo.java
@@ -53,7 +53,7 @@
      */
     public NetconfDeviceInfo(String name, String password, IpAddress ipAddress,
                              int port) {
-        Preconditions.checkArgument(!name.equals(""), "Empty device name");
+        Preconditions.checkArgument(!name.equals(""), "Empty user name");
         Preconditions.checkNotNull(port > 0, "Negative port");
         Preconditions.checkNotNull(ipAddress, "Null ip address");
         this.name = name;
@@ -73,7 +73,7 @@
      */
     public NetconfDeviceInfo(String name, String password, IpAddress ipAddress,
                              int port, String keyString) {
-        Preconditions.checkArgument(!name.equals(""), "Empty device name");
+        Preconditions.checkArgument(!name.equals(""), "Empty user name");
         Preconditions.checkNotNull(port > 0, "Negative port");
         Preconditions.checkNotNull(ipAddress, "Null ip address");
         this.name = name;