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/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/AbstractP4RuntimeHandlerBehaviour.java b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/AbstractP4RuntimeHandlerBehaviour.java
index 90e7a31..7f9c8c6 100644
--- a/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/AbstractP4RuntimeHandlerBehaviour.java
+++ b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/AbstractP4RuntimeHandlerBehaviour.java
@@ -48,9 +48,9 @@
     private static final String DEVICE_REQ_TIMEOUT = "deviceRequestTimeout";
     private static final int DEFAULT_DEVICE_REQ_TIMEOUT = 60;
 
-    public static final String P4RUNTIME_SERVER_ADDR_KEY = "p4runtime_ip";
-    public static final String P4RUNTIME_SERVER_PORT_KEY = "p4runtime_port";
-    public static final String P4RUNTIME_DEVICE_ID_KEY = "p4runtime_deviceId";
+    private static final String P4RUNTIME_SERVER_ADDR_KEY = "p4runtime_ip";
+    private static final String P4RUNTIME_SERVER_PORT_KEY = "p4runtime_port";
+    private static final String P4RUNTIME_DEVICE_ID_KEY = "p4runtime_deviceId";
 
     protected final Logger log = LoggerFactory.getLogger(getClass());
 
@@ -61,7 +61,7 @@
     protected P4RuntimeController controller;
     protected PiPipeconf pipeconf;
     protected P4RuntimeClient client;
-    protected PiTranslationService piTranslationService;
+    protected PiTranslationService translationService;
 
     /**
      * Initializes this behaviour attributes. Returns true if the operation was
@@ -102,7 +102,7 @@
         }
         pipeconf = piPipeconfService.getPipeconf(pipeconfId).get();
 
-        piTranslationService = handler().get(PiTranslationService.class);
+        translationService = handler().get(PiTranslationService.class);
 
         return true;
     }
@@ -158,8 +158,8 @@
             return null;
         }
 
-        P4RuntimeClientKey clientKey = new
-                P4RuntimeClientKey(deviceId, serverAddr, serverPort, p4DeviceId);
+        final P4RuntimeClientKey clientKey = new P4RuntimeClientKey(
+                deviceId, serverAddr, serverPort, p4DeviceId);
         if (!controller.createClient(clientKey)) {
             log.warn("Unable to create client for {}, aborting operation", deviceId);
             return null;
@@ -176,7 +176,7 @@
      * @param defaultVal default value
      * @return boolean
      */
-    protected boolean driverBoolProperty(String propName, boolean defaultVal) {
+    boolean driverBoolProperty(String propName, boolean defaultVal) {
         checkNotNull(propName);
         if (handler().driver().getProperty(propName) == null) {
             return defaultVal;