assertEquals("2004-04-01T12:34:56.123Z", FessFunctions.formatDate(date));

        date = FessFunctions.parseDate("2004-04-01T12:34:56Z");
        assertEquals("2004-04-01T12:34:56.000Z", FessFunctions.formatDate(date));

        date = FessFunctions.parseDate("2004-04-01T12:34Z");
        assertEquals("2004-04-01T12:34:00.000Z", FessFunctions.formatDate(date));

        date = FessFunctions.parseDate("2004-04-01");

          headersOf(
            "Last-Modified",
            formatDate(-1, TimeUnit.HOURS)!!,
            "Expires",
            formatDate(1, TimeUnit.HOURS)!!,
          ),
        body = "ABC.1",
      ),
    )
    server.enqueue(
      MockResponse(
        headers =
          headersOf(
            "Last-Modified",
            formatDate(-1, TimeUnit.HOURS)!!,
            "Expires",

                    throw new InvalidAccessTokenException("invalid_token",
                            "The token is expired(" + FessFunctions.formatDate(FessFunctions.date(expiredTime)) + ").");
                }
                stream(accessToken.getPermissions()).of(stream -> stream.forEach(permissionSet::add));

     */
    protected StringBuilder appendTimestamp(final StringBuilder buf) {
        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();
        append(buf, "timestamp", () -> FessFunctions.formatDate(systemHelper.getCurrentTime()));
        return buf;
    }

    /**
     * Appends exception information to the buffer.
     *
     * @param buf the string buffer to append to