code: public void addImageToCell(long sheetId, long rowId, long columnId, String file, String fileType) throws FileNotFoundException, SmartsheetException {
          addImage("sheets/" + sheetId + "/rows/" + rowId + "/columns/" + columnId + "/cellimages", file, fileType, false, null);
      }
docs: Add an image to a cell.
  
  It mirrors the following Smartsheet REST API method: POST /sheets/{sheetId}/rows/{rowId}/columns/{columnId}/cellimages
  
  Exceptions:
  InvalidRequestException : if there is any problem with the REST API request
  AuthorizationException : if there is any problem with the REST API authorization(access token)
  ResourceNotFoundException : if the resource can not be found
  ServiceUnavailableException : if the REST API service is not available (possibly due to rate limiting)
  SmartsheetRestException : if there is any other REST API related error occurred during the operation
  SmartsheetException : if there is any other error occurred during the operation
  
  @param sheetId the sheet Id
  @param rowId the row id
  @param columnId the column id
  @param file the file path
  @param fileType
  @throws SmartsheetException the smartsheet exception
  @throws FileNotFoundException image file not found