ONOS-1798: More appropriate method name + better pre-condition checks

Change-Id: I5d277967c22b9db48097288ea072cbc4d1c5a2a8
diff --git a/core/api/src/main/java/org/onosproject/cluster/LeadershipService.java b/core/api/src/main/java/org/onosproject/cluster/LeadershipService.java
index c228d32..9b94056 100644
--- a/core/api/src/main/java/org/onosproject/cluster/LeadershipService.java
+++ b/core/api/src/main/java/org/onosproject/cluster/LeadershipService.java
@@ -74,7 +74,8 @@
      * potentially become the leader again if and when it becomes the highest
      * priority candidate
      * <p>
-     * If the local nodeId is not the leader, this method will be a noop.
+     * If the local nodeId is not the leader, this method will make no changes and
+     * simply return false.
      *
      * @param path topic for which this controller node should give up leadership
      * @return true if this node stepped down from leadership, false otherwise