dictionaries where the keys are strings - additionalProperties as object

[qwert666]

Hi

I'm having a problem with an openapi.json specification that contains a response defined as a object that can have keys as strings, something like in the Swagger doc - Value Type

API response

{
"data": {
    "fooId": "123",
     "bar": "abc"
   }
}

External API that I don't have control over, defines:

OpenApi.json

"responses": {
   "200": {
       "description": "Returns additional data.",
        "content": {
            "application/json": {
                "schema": {
                   "$ref": "#/components/schemas/AdditionalChainData"
              },
       ...
"AdditionalChainData": {
        "type": "object",
        "properties": {
          "data": {
            "type": "object",
            "additionalProperties": {
              "type": "object",
              "properties": {
                "key": {
                  "type": "string",
                  "maxLength": 30
                },
                "value": {
                  "type": "string",
                  "maxLength": 200
                }
              }
            }
          }
        }
      }

The returned model seems wrong as it expect explicit attributes "key" and "value"

@attr.s(auto_attribs=True)
class AdditionalChainData:
    """
    Attributes:
        data (Union[Unset, AdditionalChainDataData]):
    """

    data: Union[Unset, "AdditionalChainDataData"] = UNSET 


@attr.s(auto_attribs=True)
class AdditionalChainDataData:
    """ """

    additional_properties: Dict[str, "AdditionalChainDataDataAdditionalProperty"] = attr.ib(init=False, factory=dict)
    
@attr.s(auto_attribs=True)
class AdditionalChainDataDataAdditionalProperty:
    """
    Attributes:
        key (Union[Unset, str]):
        value (Union[Unset, str]):
    """

    key: Union[Unset, str] = UNSET
    value: Union[Unset, str] = UNSET

I could not find any end 2 end test for this case of specification for additionalProperties. Is this a expected model output or probably a bug?