Add CLI command to view groups on switches

Change-Id: I0ce3cca85e8b38d2e713bf1f0abd4303629e15e4
diff --git a/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java b/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
index 1490b0b..2d8f81c 100644
--- a/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
+++ b/core/net/src/main/java/org/onosproject/net/group/impl/GroupManager.java
@@ -15,13 +15,7 @@
  */
 package org.onosproject.net.group.impl;
 
-import static org.slf4j.LoggerFactory.getLogger;
-
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.Set;
-
+import com.google.common.collect.Sets;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -54,7 +48,12 @@
 import org.onosproject.net.provider.AbstractProviderService;
 import org.slf4j.Logger;
 
-import com.google.common.collect.Sets;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Set;
+
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
  * Provides implementation of the group service APIs.
@@ -206,6 +205,11 @@
         return store.getGroups(deviceId);
     }
 
+    @Override
+    public Iterable<Group> getGroups(DeviceId deviceId) {
+        return store.getGroups(deviceId);
+    }
+
     /**
      * Adds the specified group listener.
      *