@Override
      public List<ServerName> getOnlineServersListWithPredicator(List<ServerName> servers,
        Predicate<ServerMetrics> filter) {
        return idleServers;
      }
Test the cluster startup bulk assignment which attempts to retain assignment info.
hbase-balancer/src/test/java/org/apache/hadoop/hbase/master/balancer/TestBaseLoadBalancer.java