public static int mask(int crc) {
        // Rotate right by 15 bits and add a constant.
        return ((crc >>> 15) | (crc << 17)) + MASK_DELTA;
    }
Return a masked representation of crc.
<p/>
Motivation: it is problematic to compute the CRC of a string that contains embedded CRCs. Therefore we recommend
that CRCs stored somewhere (e.g., in files) should be masked before being stored.
node/etl/src/main/java/com/alibaba/otter/node/etl/common/io/signature/Crc32C.java