added more mastership-related interfaces

Change-Id: I3c5da1e2a4346d6e557232c5f896b32a7268ec39
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
index e0d2756..a835449 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
@@ -4,7 +4,7 @@
 import org.onlab.onos.net.DeviceId;
 
 /**
- * Describes infrastructure device event.
+ * Describes a device mastership event.
  */
 public class MastershipEvent extends AbstractEvent<MastershipEvent.Type, DeviceId> {