[ONOS-7584] Adding Capability of re-connecting to a P4Runtime Device.
Also addresses ONOS-7359

Change-Id: I47ec4ed429af82feb225ab5ac180b94c91366a53
diff --git a/core/api/src/main/java/org/onosproject/net/device/DeviceHandshaker.java b/core/api/src/main/java/org/onosproject/net/device/DeviceHandshaker.java
index eb3c19c..606248a 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DeviceHandshaker.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DeviceHandshaker.java
@@ -46,4 +46,22 @@
      */
     CompletableFuture<MastershipRole> roleChanged(MastershipRole newRole);
 
+    /**
+     * Applies a listener to a channel established with the device.
+     *
+     * @param listener the channel listener
+     */
+    default void addChannelListener(ChannelListener listener) {
+        throw new UnsupportedOperationException("Listener Registration not supported");
+    }
+
+    /**
+     * Removes a listener to a channel established with the device.
+     *
+     * @param listener the channel listener
+     */
+    default void removeChannelListener(ChannelListener listener) {
+        throw new UnsupportedOperationException("Listener Removal not supported");
+    }
+
 }