private static void throwNumberFormatException(byte[] data, int offset, int len) {
        try {
            throw new NumberFormatException("For input string: \"" + new String(data, offset, len, UTF8_NAME) + "\"");
        } catch (UnsupportedEncodingException e) {
            throw Throwables.propagate(e);
        }
    }
According to {@link Long#parseLong(String)}.
indexr-common/src/main/java/io/indexr/util/UTF8Util.java