ONOS-7050 Refactored PI translation service and store

The translation store is now able to maintain mappings between
translated entities and specific instances of a PI entry in the network
(i.e. applied to a device).

The translation service has been refactored to allow users to
learn and forget translated entities.

The refactoring of the P4Runtime driver using this service will be
submitted separatelly.

Change-Id: Iaafd87d90232514853ca0dea0115dbae4f6e7886
diff --git a/core/api/src/main/java/org/onosproject/net/group/Group.java b/core/api/src/main/java/org/onosproject/net/group/Group.java
index 3e2494c..39c6a3d 100644
--- a/core/api/src/main/java/org/onosproject/net/group/Group.java
+++ b/core/api/src/main/java/org/onosproject/net/group/Group.java
@@ -16,11 +16,12 @@
 package org.onosproject.net.group;
 
 import org.onosproject.core.GroupId;
+import org.onosproject.net.pi.service.PiTranslatable;
 
 /**
  * ONOS representation of group that is stored in the system.
  */
-public interface Group extends GroupDescription {
+public interface Group extends GroupDescription, PiTranslatable {
     /**
      * State of the group object in ONOS.
      */