@Override
    public String toString() {
        if (value >= 0) {
            return Long.toString(value);
        } else {
            return BigInteger.valueOf(value & Long.MAX_VALUE).add(MAX_VALUE_LONG).toString();
        }
    }
Create an <code>unsigned long</code>

@throws NumberFormatException If <code>value</code> is not in the range
                              of an <code>unsigned long</code>
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/onenote/fsshttpb/unsigned/ULong.java