I expect it should work:
```
:) select CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

SELECT CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

Query id: fb057b45-b72a-4d22-9b38-a3136cdf2465


0 rows in set. Elapsed: 0.002 sec.

Received exception from server (version 22.5.1):
Code: 53. DB::Exception: Received from localhost:9000. DB::Exception: Cast to Object can be performed only from flatten named Tuple, Map or String. Got: Object('json'): While processing CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))'). (TYPE_MISMATCH)
```

@CurtizJ what do you think?
Additions additions [[maybe_unused]] = Additions())
    {
        using ColVecTo = typename ToDataType::ColumnType;
        const DateLUTImpl * local_time_zone [[maybe_unused]] = nullptr;
        const DateLUTImpl * utc_time_zone [[maybe_unused]] = nullptr;
        
        if constexpr (std::is_same_v<ToDataType, DataTypeDateTime> || to_datetime64)
        {
            const auto result_type = removeNullable(res_type);
            
            if (const auto dt_col = checkAndGetDataType<ToDataType>(result_type.get()))
                local_time_zone = &dt_col->getTimeZone();
            else
            {
                local_time_zone = &extractTimeZoneFromFunctionArguments(arguments, 1, 0);
            }
            if constexpr (parsing_mode == ConvertFromStringParsingMode::BestEffort || parsing_mode == ConvertFromStringParsingMode::BestEffortUS)
                utc_time_zone = &DateLUT::instance("UTC");
        }
        const IColumn * col_from = arguments[0].column.get();
        const ColumnString * col_from_string = checkAndGetColumn<ColumnString>(col_from);
        const ColumnFixedString * col_from_fixed_string = checkAndGetColumn<ColumnFixedString>(col_from);
        if (std::is_same_v<FromDataType, DataTypeString> && !col_from_string)
            throw Exception("Illegal column " + col_from->getName()
                + " of first argument of function " + Name::name,
                ErrorCodes::ILLEGAL_COLUMN);
        if (std::is_same_v<FromDataType, DataTypeFixedString> && !col_from_fixed_string)