public boolean getRejectDecommissionedHostsConfig(Configuration conf) {
    return conf.getBoolean(HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY,
      HConstants.REJECT_DECOMMISSIONED_HOSTS_DEFAULT);
  }
Reads the value of HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY from the config and returns it
@param conf Configuration instance of the Master
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java