private String getNonEmptyConfVar(Configuration conf, String param) throws IOException {
    String val = conf.get(param);
    if (val == null || val.trim().isEmpty()) {
      throw new IOException("Configuration parameter " + param + " should be set, "
          + WHEN_ZK_DSTORE_MSG);
    }
    return val;
  }
Default constructor for dynamic instantiation w/ Configurable
(ReflectionUtils does not support Configuration constructor injection).
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/security/ZooKeeperTokenStore.java