code: public File getFileFromNewFilesToCommit(int index) {
      CheckUtilities.checkIntIndexInListRange(newFilesToCommit, index);
      return newFilesToCommit.get(index);
    }
docs: Get the name of the file from newFilesToCommit list at a given index.
  
  @param index
  Index in the list must be positive and less than the number of new files to commit.
  @return the name of the file.