public BigInteger toBigIntegerSlow() {
    BigInteger bigInt = BigInteger.valueOf(v[3] & SqlMathUtil.LONG_MASK);
    bigInt = bigInt.shiftLeft(32);
    bigInt = bigInt.add(BigInteger.valueOf(v[2] & SqlMathUtil.LONG_MASK));
    bigInt = bigInt.shiftLeft(32);
    bigInt = bigInt.add(BigInteger.valueOf(v[1] & SqlMathUtil.LONG_MASK));
    bigInt = bigInt.shiftLeft(32);
    bigInt = bigInt.add(BigInteger.valueOf(v[0] & SqlMathUtil.LONG_MASK));
    return bigInt;
  }
Convert this object to {@link BigInteger}. Do not use this method in a
performance sensitive place.

@return BigInteger to represent this object
common/src/java/org/apache/hadoop/hive/common/type/UnsignedInt128.java