default OptionalInt getDecimalDigits() {
        return getAsInt(HasDecimalDigitsUtil.DECIMAL_DIGITS);
    }
Gets the decimal digits of this {@link Document}. If no decimal digits 
value is present, this method will return an empty {@code OptionalInt}. 
This should be interpreted as no decisions can be made regarding the 
precision of the data.

@return the decimal digits of this {@link Document}
runtime-parent/runtime-config/src/main/java/com/speedment/runtime/config/trait/HasDecimalDigits.java