code: public Attachment attachFile(long sheetId, long commentId, File file, String contentType) throws FileNotFoundException,
              SmartsheetException {
          Util.throwIfNull(sheetId, commentId, file, contentType);
          Util.throwIfEmpty(contentType);
  
          return attachFile(sheetId, commentId, new FileInputStream(file), contentType, file.length(), file.getName());
      }
docs: Attach a file to a comment with simple upload.
  
  It mirrors to the following Smartsheet REST API method: POST /sheets/{sheetId}/comments/{commentId}/attachments
  
  @param sheetId the id of the sheet
  @param commentId the id of the comment
  @param file the file to attach
  @param contentType the content type of the file
  @return the created attachment
  @throws FileNotFoundException the file not found exception
  @throws IllegalArgumentException if any argument is null or empty string
  @throws InvalidRequestException if there is any problem with the REST API request
  @throws AuthorizationException if there is any problem with  the REST API authorization (access token)
  @throws ResourceNotFoundException if the resource cannot be found
  @throws ServiceUnavailableException if the REST API service is not available (possibly due to rate limiting)
  @throws SmartsheetException if there is any other error during the operation