public BigDecimal toBigDecimal() {

    // if this function is frequently used, we need to optimize this.
    return new BigDecimal(toFormalString());
  }
Converts this object to {@link BigDecimal}. This method is not supposed to
be used in a performance-sensitive place.

@return {@link BigDecimal} object equivalent to this object.
common/src/java/org/apache/hadoop/hive/common/type/Decimal128.java