ValueWriter.writeFieldValue allows BigDecimals that are too big to be written

[changlinli]

writeFieldValue has the following:

        else if(value instanceof BigDecimal) {
            writeOctet('D');
            BigDecimal decimal = (BigDecimal)value;
            writeOctet(decimal.scale());
            BigInteger unscaled = decimal.unscaledValue();
            if(unscaled.bitLength() > 32) /*Integer.SIZE in Java 1.5*/
                throw new IllegalArgumentException
                    ("BigDecimal too large to be encoded");
            writeLong(decimal.unscaledValue().intValue());
        }

but 32 is actually too permissive. It should be 31 because bitLength ignores the sign bit, meaning that writing new BigDecimal(Integer.Max_Value).add(new BigDecimal(1)) "works" (that is no exception is thrown) and yields a different number back when you read it back using ValueReader.