@RestrictedApi(explanation = "Should only be called in tests", link = "",
      allowedOnPath = ".*/src/test/.*")
  Map<Class<? extends CandidateGenerator>, CandidateGenerator> getCandidateGenerators() {
    return this.candidateGenerators;
  }
The constructor that pass a MetricsStochasticBalancer to BaseLoadBalancer to replace its
default MetricsBalancer
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java