json_str/Vertex/text.json

"contents": [
    {
      "role": string,
      "parts": [
        {
          // Union field data can be only one of the following:
          "text": string,
          "inlineData": {
            "mimeType": string,
            "data": string
          },
          "fileData": {
            "mimeType": string,
            "fileUri": string
          },
          // End of list of possible types for union field data.
          "videoMetadata": {
            "startOffset": {
              "seconds": integer,
              "nanos": integer
            },
            "endOffset": {
              "seconds": integer,
              "nanos": integer
            }
          }
        }
      ]
    }
  ],