private boolean hasEmptyBalancerPlans(Map<ServerName, List<RegionInfo>> servers) {
    Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable =
      (Map) mockClusterServersWithTables(servers);
    List<RegionPlan> plans = loadBalancer.balanceCluster(loadOfAllTable);
    return plans == null || plans.isEmpty();
  }
Data set for testLocalityCost: [test][0][0] = mapping of server to number of regions it hosts
[test][region + 1][0] = server that region is hosted on [test][region + 1][server + 1] =
locality for region on server
hbase-balancer/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancer.java