Fix balance-masters functionality in the new LeadershipService based device mastership store

Change-Id: I9f64d514cee7d5a5383fd4c2fa30a8616c97785c
diff --git a/core/api/src/test/java/org/onosproject/cluster/LeadershipServiceAdapter.java b/core/api/src/test/java/org/onosproject/cluster/LeadershipServiceAdapter.java
index 02742d4..abc92f5 100644
--- a/core/api/src/test/java/org/onosproject/cluster/LeadershipServiceAdapter.java
+++ b/core/api/src/test/java/org/onosproject/cluster/LeadershipServiceAdapter.java
@@ -73,4 +73,14 @@
     public List<NodeId> getCandidates(String path) {
         return null;
     }
-}
+
+    @Override
+    public boolean stepdown(String path) {
+        return false;
+    }
+
+    @Override
+    public boolean makeTopCandidate(String path, NodeId nodeId) {
+        return false;
+    }
+}
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