presto-main/src/main/java/io/prestosql/type/VarbinaryOperators.java/VarbinaryOperators/hashCode
class VarbinaryOperators:    @ScalarOperator(HASH_CODE)
    @SqlType(StandardTypes.BIGINT)
    public static long hashCode(@SqlType(StandardTypes.VARBINARY) Slice value)
    {
        // This needs to match the hash function for VARBINARY blocks
        // (i.e. AstractVariableWidthBlock.hash(...))
        // TODO: we need to get rid of hash from Block and rely on HASH_CODE operators only
        return xxHash64(value);
    }