*/
    protected static final String ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers";

    /**
     * CORS header for specifying allowed HTTP methods.
     */
    protected static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";

    /**
     * CORS header for allowing private network access.
     */

        assertTrue("ACCESS_CONTROL_ALLOW_HEADERS should be final", Modifier.isFinal(headersField.getModifiers()));

        Field methodsField = CorsHandler.class.getDeclaredField("ACCESS_CONTROL_ALLOW_METHODS");
        assertTrue("ACCESS_CONTROL_ALLOW_METHODS should be final", Modifier.isFinal(methodsField.getModifiers()));

        Field privateNetworkField = CorsHandler.class.getDeclaredField("ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK");

        final HttpServletResponse httpResponse = (HttpServletResponse) response;
        httpResponse.addHeader(ACCESS_CONTROL_ALLOW_ORIGIN, origin);
        httpResponse.addHeader(ACCESS_CONTROL_ALLOW_METHODS, fessConfig.getApiCorsAllowMethods());
        httpResponse.addHeader(ACCESS_CONTROL_ALLOW_HEADERS, fessConfig.getApiCorsAllowHeaders());
        httpResponse.addHeader(ACCESS_CONTROL_MAX_AGE, fessConfig.getApiCorsMaxAge());