public static NullOrdering fromSign(char sign) {
    for (NullOrdering nullOrdering : NullOrdering.values()) {
      if (nullOrdering.sign == sign) {
        return nullOrdering;
      }
    }
    throw new EnumConstantNotPresentException(NullOrdering.class, "No enum constant present with sign " + sign);
  }
Enum for converting different Null ordering description types.
ql/src/java/org/apache/hadoop/hive/ql/util/NullOrdering.java