ONOS-985: Sample integration test application for group subsystem

Change-Id: I68352f922e5c7a0800fcc4fa839955769bf925a6
diff --git a/core/api/src/main/java/org/onosproject/net/group/GroupBuckets.java b/core/api/src/main/java/org/onosproject/net/group/GroupBuckets.java
index 5ca8f30..26cd5f6 100644
--- a/core/api/src/main/java/org/onosproject/net/group/GroupBuckets.java
+++ b/core/api/src/main/java/org/onosproject/net/group/GroupBuckets.java
@@ -15,6 +15,7 @@
  */
 package org.onosproject.net.group;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import java.util.List;
@@ -66,4 +67,10 @@
         return false;
     }
 
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("buckets", buckets)
+                .toString();
+    }
 }
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