.Net: ResponseSchema not working with `ForJsonSchema` in `GeminiPromptExecutionSettings`

[RogerBarreto]

Discussed in #12234

^{Originally posted by VladyslavLishchyna May 22, 2025}
Hi community! I try to get response from Gemini as JSON object and use like this

GeminiPromptExecutionSettings executionSettings = new()
{
    FunctionChoiceBehavior = FunctionChoiceBehavior.None(),
    ResponseMimeType = "application/json",
    ResponseSchema = ChatResponseFormat.ForJsonSchema(jsonSchema)
};

And have 400 status code

Exception while start application - Microsoft.SemanticKernel.HttpOperationException: Response status code does not indicate success: 400 (Bad Request).
 ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 400 (Bad Request).
   at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode()

Schema looks like:

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Response",
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "FirstProperty": {
      "type": "integer",
      "format": "int32"
    },
    "Summary": {
      "type": "string"
    }
  }
}

If I run without ResponseSchema parameter I receive response successfully