There was the controversy spotted in the private class DigitList.

    /**
     * Utility routine to get the value of the digit list
     * If (count == 0) this throws a NumberFormatException, which
     * mimics Long.parseLong().
     */
    public final double getDouble() {
        if (count == 0) {
            return 0.0;
        }

The doc says the method throws, if count == 0, but the code does not.
Need to check what is appropriate here and correct the other part.