ONOS-3791 NETCONF session factory and exception on device connection

Change-Id: I7c6651a4f76537056a2dc8f94d54818b5b238b9a
diff --git a/protocols/netconf/ctl/src/main/java/org/onosproject/netconf/ctl/NetconfControllerImpl.java b/protocols/netconf/ctl/src/main/java/org/onosproject/netconf/ctl/NetconfControllerImpl.java
index cdcfbf8..251a74b 100644
--- a/protocols/netconf/ctl/src/main/java/org/onosproject/netconf/ctl/NetconfControllerImpl.java
+++ b/protocols/netconf/ctl/src/main/java/org/onosproject/netconf/ctl/NetconfControllerImpl.java
@@ -46,7 +46,7 @@
     public static final Logger log = LoggerFactory
             .getLogger(NetconfControllerImpl.class);
 
-    public Map<DeviceId, NetconfDevice> netconfDeviceMap = new ConcurrentHashMap<>();
+    private Map<DeviceId, NetconfDevice> netconfDeviceMap = new ConcurrentHashMap<>();
 
     protected Set<NetconfDeviceListener> netconfDeviceListeners = new CopyOnWriteArraySet<>();
 
@@ -130,6 +130,4 @@
     public Map<DeviceId, NetconfDevice> getDevicesMap() {
         return netconfDeviceMap;
     }
-
-
 }