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?
{
        auto getter = [&] (const auto & args) { return getReturnTypeImplRemovedNullable(args); };
        auto res = getReturnTypeDefaultImplementationForNulls(arguments, getter);
        to_nullable = res->isNullable();
        checked_return_type = true;
        return res;
    }
    DataTypePtr getReturnTypeImplRemovedNullable(const ColumnsWithTypeAndName & arguments) const
    {
        FunctionArgumentDescriptors mandatory_args = {{"Value", nullptr, nullptr, nullptr}};
        FunctionArgumentDescriptors optional_args;
        if constexpr (to_decimal)
        {
            mandatory_args.push_back({"scale", &isNativeInteger<IDataType>, &isColumnConst, "const Integer"});
        }
        if (!to_decimal && isDateTime64<Name, ToDataType>(arguments))
        {
            mandatory_args.push_back({"scale", &isNativeInteger<IDataType>, &isColumnConst, "const Integer"});
        }