try {
            final char[] buf = new char[DEFAULT_BUF_SIZE];
            int len;
            int amount = 0;
            while ((len = in.read(buf)) != -1) {
                out.append(buf, 0, len);
                amount += len;
            }
            return amount;
        } catch (final IOException e) {
            throw new IORuntimeException(e);
        }
    }