[Feature] support dictionaries in pydantic basemodels for json (via additionalProperties)

[Ben-Epstein]

Environment details

Programming language: python
OS: macos/linux
Language runtime version: python 3.10
Package version: 0.3.0

Steps to reproduce

from google import genai
from google.genai import types
from pydantic import BaseModel

class Answer(BaseModel):
  foo: dict[str, int]

project_id = ""
client = genai.Client(vertexai=True, project=project_id, location="us-central1")
cfg = types.GenerateContentConfig(
            response_schema=Answer,
            response_mime_type="application/json",
            temperature=0.0,
            seed=42,
        )
res = client.models.generate_content(model="gemini-1.5-flash-002", config=cfg, contents="Pick a value for foo")

ValidationError: 1 validation error for Schema
properties.foo.additionalProperties
  Extra inputs are not permitted [type=extra_forbidden, input_value={'type': 'INTEGER'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.10/v/extra_forbidden

see: https://www.learnjsonschema.com/2020-12/applicator/additionalproperties/

[happy-qiao]

Hi Ben.

additionalProperties is not supported by API backend. We're working on adding this feature and hope to have it ready soon.

Thanks