code: public BigDecimal optBigDecimal(int index, BigDecimal defaultValue) {
  		try {
  			return this.getBigDecimal(index);
  		} catch (Exception e) {
  			return defaultValue;
  		}
  	}
docs: Get the optional BigDecimal value associated with an index. The
  defaultValue is returned if there is no value for the index, or if the
  value is not a number and cannot be converted to a number.
  
  @param index The index must be between 0 and length() - 1.
  @param defaultValue The default value.
  @return The value.