Cherry pick gNMI and Stratum related changes to this branch

Cherry picked commits:
20211 Update gNMI version and build script
20247 [ONOS-7829] Implement AbstractGrpcClient and AbstractGrpcClientControl
20233 [ONOS-7141][ONOS-7142] Add GnmiClient and GnmiController
20234 Refactor OpenConfig gNMI device description descovery
20260 [ONOS-7831] Implement GnmiHandshaker
20270 Add Stratum driver

Change-Id: I81ad8bce45251af5909cfcac0edbcfd11c8ebf1d
diff --git a/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/AbstractGrpcClientController.java b/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/AbstractGrpcClientController.java
index 36e453c..bf2bbf1 100644
--- a/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/AbstractGrpcClientController.java
+++ b/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/AbstractGrpcClientController.java
@@ -21,7 +21,6 @@
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
 import io.grpc.netty.NettyChannelBuilder;
-
 import org.onosproject.event.AbstractListenerManager;
 import org.onosproject.event.Event;
 import org.onosproject.event.EventListener;
@@ -152,7 +151,7 @@
         return withDeviceLock(() -> doGetClient(deviceId), deviceId);
     }
 
-    protected C doGetClient(DeviceId deviceId) {
+    private C doGetClient(DeviceId deviceId) {
         if (!clientKeys.containsKey(deviceId)) {
             return null;
         }
@@ -183,7 +182,7 @@
         return withDeviceLock(() -> doIsReachable(deviceId), deviceId);
     }
 
-    protected boolean doIsReachable(DeviceId deviceId) {
+    private boolean doIsReachable(DeviceId deviceId) {
         // Default behaviour checks only the gRPC channel, should
         // check according to different gRPC service
         if (!clientKeys.containsKey(deviceId)) {