*     helpful predefined constants
   * @return the buffered writer
   */
  public static BufferedWriter newWriter(File file, Charset charset) throws FileNotFoundException {
    checkNotNull(file);
    checkNotNull(charset);
    return new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset));
  }

  /**

   *     helpful predefined constants
   * @return the buffered writer
   */
  public static BufferedWriter newWriter(File file, Charset charset) throws FileNotFoundException {
    checkNotNull(file);
    checkNotNull(charset);
    return new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset));
  }

  /**

    }

    /**
     * 必要があればライターを{@link BufferedWriter}でラップします。
     *
     * @param writer
     *            ライター
     * @return ラップされたライター
     */
    protected static Writer wrap(final Writer writer) {
        if (writer instanceof BufferedWriter) {
            return writer;
        }
        if (writer instanceof StringWriter) {