MasteshipService, store, and CLI commands use RoleInfo

Change-Id: Ibc569498a67d33d088e5c9f89c6bb1f45eadc26e
diff --git a/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java b/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
index 7b8531c..9f75fc4 100644
--- a/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
@@ -56,7 +56,10 @@
     }
 
     /**
-     * Returns the NodeID of the node responsible for triggering the event.
+     * Returns the NodeID of the node associated with the event.
+     * For MASTER_CHANGED this is the newly elected master, and for
+     * BACKUPS_CHANGED, this is the node that was newly added, removed, or
+     * whose position was changed in the list.
      *
      * @return node ID as a subject
      */
diff --git a/core/api/src/main/java/org/onlab/onos/mastership/MastershipService.java b/core/api/src/main/java/org/onlab/onos/mastership/MastershipService.java
index 224bc05..30cb545 100644
--- a/core/api/src/main/java/org/onlab/onos/mastership/MastershipService.java
+++ b/core/api/src/main/java/org/onlab/onos/mastership/MastershipService.java
@@ -1,9 +1,9 @@
 package org.onlab.onos.mastership;
 
-import java.util.List;
 import java.util.Set;
 
 import org.onlab.onos.cluster.NodeId;
+import org.onlab.onos.cluster.RoleInfo;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.MastershipRole;
 
@@ -57,7 +57,7 @@
      * @param deviceId the identifier of the device
      * @return a list of controller IDs
      */
-    List<NodeId> getNodesFor(DeviceId deviceId);
+    RoleInfo getNodesFor(DeviceId deviceId);
 
     /**
      * Returns the devices for which a controller is master.
diff --git a/core/api/src/main/java/org/onlab/onos/mastership/MastershipStore.java b/core/api/src/main/java/org/onlab/onos/mastership/MastershipStore.java
index 5e7b0e4..bd7a354 100644
--- a/core/api/src/main/java/org/onlab/onos/mastership/MastershipStore.java
+++ b/core/api/src/main/java/org/onlab/onos/mastership/MastershipStore.java
@@ -1,9 +1,9 @@
 package org.onlab.onos.mastership;
 
-import java.util.List;
 import java.util.Set;
 
 import org.onlab.onos.cluster.NodeId;
+import org.onlab.onos.cluster.RoleInfo;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.MastershipRole;
 import org.onlab.onos.store.Store;
@@ -42,13 +42,12 @@
     NodeId getMaster(DeviceId deviceId);
 
     /**
-     * Returns the controllers connected to a device, in mastership-
-     * preference order.
+     * Returns the master and backup nodes for a device.
      *
      * @param deviceId the device identifier
-     * @return an ordered list of controller IDs
+     * @return a RoleInfo containing controller IDs
      */
-    List<NodeId> getNodes(DeviceId deviceId);
+    RoleInfo getNodes(DeviceId deviceId);
 
     /**
      * Returns the devices that a controller instance is master of.