import base64
import json

class HTTPApiDecoder:
    # Existing class content...

    @staticmethod
    def decode_specific_asset_ids(encoded_ids: str):
        # Decoding from base64url and transforming to JSON
        decoded_json = base64.urlsafe_b64decode(encoded_ids + '===').decode('utf-8')
        # Assuming the JSON represents a list of SpecificAssetId objects
        specific_asset_ids = json.loads(decoded_json)
        # Transform the list of dictionaries into SpecificAssetId instances
        return [model.SpecificAssetId(**id_dict) for id_dict in specific_asset_ids]

def get_aas_all(self, request: Request, url_args: Dict, **_kwargs) -> Response:
    response_t = get_response_type(request)
    aas: Iterator[model.AssetAdministrationShell] = self._get_all_obj_of_type(model.AssetAdministrationShell)

    # Filter by 'idShort' if the parameter is provided in the request
    id_short = request.args.get("idShort")
    if id_short is not None:
        aas = filter(lambda shell: shell.id_short == id_short, aas)
    
    # Filtering by base64url encoded SpecificAssetIds if provided
    asset_ids = request.args.get("assetIds")
    if asset_ids is not None:
        # Use the new method to decode and instantiate SpecificAssetIds
        spec_asset_ids = HTTPApiDecoder.decode_specific_asset_ids(asset_ids)
        # Filter the AAS based on these SpecificAssetIds
        aas = filter(lambda shell: all(spec_id in [id_.identifier for id_ in shell.specific_asset_ids] for spec_id in spec_asset_ids), aas)
    
    aas_list = list(aas)
    return response_t(aas_list)