boolean blackListed(Configuration conf, String name) {
    if (blackListedConfEntries == null) {
      blackListedConfEntries = new HashSet<String>();
      if (conf != null) {
        String bl = conf.get(HiveConf.ConfVars.HIVE_SCRIPT_ENV_BLACKLIST.toString(),
          HiveConf.ConfVars.HIVE_SCRIPT_ENV_BLACKLIST.getDefaultValue());
        if (bl != null && !bl.isEmpty()) {
          String[] bls = bl.split(",");
          Collections.addAll(blackListedConfEntries, bls);
        }
      }
    }
    return blackListedConfEntries.contains(name);
  }
Checks whether a given configuration name is blacklisted and should not be converted
to an environment variable.
ql/src/java/org/apache/hadoop/hive/ql/exec/ScriptOperator.java