sendThreadDiscussionMessage

mutation SendThreadDiscussionMessage($input: SendThreadDiscussionMessageInput!) {
  sendThreadDiscussionMessage(input: $input) {
    threadDiscussionMessage {
      id
      threadDiscussionId
      type
      text
      slackMessageLink
      attachments {
        id
        fileName
        fileSize {
          __typename
        }
        fileExtension
        fileMimeType
        type
      }
    }
    error {
      message
      type
      code
      fields {
        field
        message
        type
      }
    }
  }
}

{
  "input": {
    "threadDiscussionId": "id",
    "markdownContent": "string"
  }
}

{
  "data": {
    "sendThreadDiscussionMessage": {
      "threadDiscussionMessage": {
        "id": "id",
        "threadDiscussionId": "id",
        "type": "INBOUND",
        "text": "string",
        "slackMessageLink": "string",
        "attachments": [
          {
            "id": "id",
            "fileName": "string",
            "fileSize": {
              "__typename": "FileSize"
            },
            "fileExtension": "string",
            "fileMimeType": "string",
            "type": "EMAIL"
          }
        ]
      },
      "error": {
        "message": "string",
        "type": "VALIDATION",
        "code": "string",
        "fields": [
          {
            "field": "string",
            "message": "string",
            "type": "VALIDATION"
          }
        ]
      }
    }
  }
}