@Override
  public void onConfigurationChange(Configuration conf) {
    final boolean newValue = getRejectDecommissionedHostsConfig(conf);
    if (rejectDecommissionedHostsConfig == newValue) {
      // no-op
      return;
    }

    LOG.info("Config Reload for RejectDecommissionedHosts. previous value: {}, new value: {}",
      rejectDecommissionedHostsConfig, newValue);

    rejectDecommissionedHostsConfig = newValue;
  }
Implementation of the ConfigurationObserver interface. We are interested in live-loading the
configuration value of HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY
@param conf Server configuration instance
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java