Distributed group store using eventual consistent map abstraction

Change-Id: I618a0f6fa80e0e25285d7a2026032f09ba90aa70
diff --git a/core/api/src/main/java/org/onosproject/net/group/GroupKey.java b/core/api/src/main/java/org/onosproject/net/group/GroupKey.java
index da8d449..9c87b83 100644
--- a/core/api/src/main/java/org/onosproject/net/group/GroupKey.java
+++ b/core/api/src/main/java/org/onosproject/net/group/GroupKey.java
@@ -17,8 +17,15 @@
 
 /**
  * Representation of generalized Key that would be used to store
- * groups in < Key, Value > store. Implementation of this interface
- * MUST override "equals()" and "hashcode()" methods.
+ * groups in < Key, Value > store. This key uses a generic
+ * byte array so that applications can associate their groups with
+ * any of their data by translating it into a byte array.
  */
 public interface GroupKey  {
+    /**
+     * Returns the byte representation of key.
+     *
+     * @return byte array
+     */
+    public byte[] key();
 }