public static String getFilename(String path) {
        if (path == null) {
            return null;
        }
        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
    }
Extract the filename from the given path.

@param path the file path (may be {@code null})
@return the extracted filename, or {@code null} if none
src/main/java/spark/utils/StringUtils.java