code: public File getAddedFile(int index) {
      CheckUtilities.checkIntIndexInListRange(addedFiles, index);
      return addedFiles.get(index);
    }
docs: Returns the file at a given location in the addedFiles list
  
  @param index
  in the list and should be positive and less than no. of files added.
  @return added file at the index in addedFiles list.