mutation ImportThreadMessages($input: ImportThreadMessagesInput!) {
  importThreadMessages(input: $input) {
    results {
      threadMessage {
        __typename
        ... on TimelineEntry {
          __typename
        }
      }
      result
      error {
        message
        type
        code
        fields {
          __typename
        }
      }
    }
    error {
      message
      type
      code
      fields {
        field
        message
        type
      }
    }
  }
}

{
  "input": {
    "threadId": "id",
    "threadMessages": [
      {
        "author": {},
        "text": "string",
        "createdAt": "string",
        "type": "INBOUND",
        "externalId": "id"
      }
    ]
  }
}

{
  "data": {
    "importThreadMessages": {
      "results": [
        {
          "threadMessage": {
            "__typename": "TimelineEntry"
          },
          "result": "UPDATED",
          "error": {
            "message": "string",
            "type": "VALIDATION",
            "code": "string",
            "fields": [
              {
                "__typename": "MutationFieldError"
              }
            ]
          }
        }
      ],
      "error": {
        "message": "string",
        "type": "VALIDATION",
        "code": "string",
        "fields": [
          {
            "field": "string",
            "message": "string",
            "type": "VALIDATION"
          }
        ]
      }
    }
  }
}