@Override
  public String getUserName() {
    String newUserName = sessionState.getConf().get("user.name", "").trim();
    if (newUserName.isEmpty()) {
      return System.getProperty("user.name");
    } else {
      return newUserName;
    }
  }
Authenticator to be used for testing and debugging. This picks the user.name
set in SessionState config, if that is null, it returns value of
System property user.name
ql/src/java/org/apache/hadoop/hive/ql/security/SessionStateConfigUserAuthenticator.java