* This is used to determine the deployment environment (e.g., "docker").
     *
     * @return the application type string, or empty string if not set
     */
    public static String getAppType() {
        final String appType = System.getenv(FESS_APP_TYPE);
        if (StringUtil.isNotBlank(appType)) {
            return appType;
        }
        return StringUtil.EMPTY;
    }

    /**

        String originalAppType = System.getenv("FESS_APP_TYPE");

        // Since we can't modify environment variables directly,
        // we test the current behavior
        String appType = ResourceUtil.getAppType();
        assertNotNull(appType);
        // appType should be either empty string or the actual env value
        assertTrue(appType.isEmpty() || appType.length() > 0);
    }