presto-main/src/main/java/io/prestosql/type/UuidOperators.java/UuidOperators/castFromUuidToVarchar
class UuidOperators:    @ScalarOperator(CAST)
    @SqlType(StandardTypes.VARCHAR)
    public static Slice castFromUuidToVarchar(@SqlType(StandardTypes.UUID) Slice slice)
    {
        return utf8Slice(new java.util.UUID(slice.getLong(0), slice.getLong(SIZE_OF_LONG)).toString());
    }