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/gnmi/api/src/main/java/org/onosproject/gnmi/api/GnmiClient.java b/protocols/gnmi/api/src/main/java/org/onosproject/gnmi/api/GnmiClient.java
index 242bc94..5beb238 100644
--- a/protocols/gnmi/api/src/main/java/org/onosproject/gnmi/api/GnmiClient.java
+++ b/protocols/gnmi/api/src/main/java/org/onosproject/gnmi/api/GnmiClient.java
@@ -17,10 +17,9 @@
 package org.onosproject.gnmi.api;
 
 import com.google.common.annotations.Beta;
-
 import gnmi.Gnmi.CapabilityResponse;
-import gnmi.Gnmi.GetResponse;
 import gnmi.Gnmi.GetRequest;
+import gnmi.Gnmi.GetResponse;
 import gnmi.Gnmi.SetRequest;
 import gnmi.Gnmi.SetResponse;
 import org.onosproject.grpc.api.GrpcClient;
@@ -34,15 +33,14 @@
 public interface GnmiClient extends GrpcClient {
 
     /**
-     * Gets capability from a target. This allows device driver behavior
-     * to validate the service version and models which gNMI device supported.
+     * Gets capability from a target.
      *
      * @return the capability response
      */
     CompletableFuture<CapabilityResponse> capability();
 
     /**
-     * Retrieve a snapshot of data from the device.
+     * Retrieves a snapshot of data from the device.
      *
      * @param request the get request
      * @return the snapshot of data from the device