@Override
      protected boolean inRange(String value, Object lower, Object upper) {
        int ivalue = Integer.parseInt(value);
        if (lower != null && ivalue < (Integer)lower) {
          return false;
        }
        if (upper != null && ivalue > (Integer)upper) {
          return false;
        }
        return true;
      }
validate value for a ConfVar, return non-null string for fail message
common/src/java/org/apache/hadoop/hive/conf/Validator.java