Gemini 图片生成请求体-Messages

{
    "model": "google/gemini-3-pro-image-preview",
    "system": "string",
    "messages": [
        {
            "text": "string",
            "image": "string"
        }
    ],
    "aspect_ratio": "1:1",
    "response_modalities": [
        "string"
    ],
    "size": "1K"
}