return buf.toString();
        };
        final String message;
        if (Constants.TRUE.equalsIgnoreCase(ComponentUtil.getFessConfig().getApiJsonResponseExceptionIncluded())) {
            message = escapeJsonKeyValue(MESSAGE_FIELD, stacktraceString.get());
        } else {
            final String errorCode = UUID.randomUUID().toString();
            message = escapeJsonKeyValue("error_code:", errorCode);