public String getLoginUrl() {
        return loginUrl;
    }
Returns the application's login URL to be assigned to all acquired Filters that subclass
{@link AccessControlFilter} or {@code null} if no value should be assigned globally. The default value
is {@code null}.

@return the application's login URL to be assigned to all acquired Filters that subclass
{@link AccessControlFilter} or {@code null} if no value should be assigned globally.
@see #setLoginUrl
support/spring/src/main/java/org/apache/shiro/spring/web/ShiroFilterFactoryBean.java