ONOS-985: Sample integration test application for group subsystem

Change-Id: I68352f922e5c7a0800fcc4fa839955769bf925a6
diff --git a/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java b/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java
index 8d374c1..385a5d6 100644
--- a/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java
+++ b/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.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.Objects;
@@ -168,4 +169,13 @@
         return false;
     }
 
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("deviceId", deviceId)
+                .add("type", type)
+                .add("buckets", buckets)
+                .add("appId", appId)
+                .toString();
+    }
 }
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