public static boolean isServletRequestAuthenticatorInstanceOf(Class<? extends ServletRequestAuthenticator> clazz) {
        final AuthCheckFilter instance = getInstance();
        if (instance == null) {
            // We've not yet been instantiated
            return false;
        }
        return servletRequestAuthenticator != null && clazz.isAssignableFrom(servletRequestAuthenticator.getClass());
    }
@Test
    public void willReturnFalseIfTheWrongServletRequestAuthenticatorIsConfigured() {

        AuthCheckFilter.SERVLET_REQUEST_AUTHENTICATOR.setValue(NormalUserServletAuthenticatorClass.class);
        new AuthCheckFilter(adminManager, loginLimitManager);

        assertThat(AuthCheckFilter.isServletRequestAuthenticatorInstanceOf(AdminUserServletAuthenticatorClass.class), is(false));
    }