docs: public static byte[] integerToBytes(BigInteger s, int length) {
        byte[] bytes = s.toByteArray();
        if (length < bytes.length) {
           // The length is smaller than the byte representation. Truncate by
           // copying over the least significant bytes
           byte[] tmp = new byte[length];
           System.arraycopy(bytes, bytes.length - tmp.length, tmp, 0, tmp.length);
           return tmp;
        } else if (length > bytes.length) {
           // The length is larger than the byte representation. Copy over all
           // bytes and leave it prefixed by zeros.
           byte[] tmp = new byte[length];
           System.arraycopy(bytes, 0, tmp, tmp.length - bytes.length, bytes.length);
           return tmp;
        }
        return bytes;
     }