public void setUnauthorizedUrl(String unauthorizedUrl) {
        this.unauthorizedUrl = unauthorizedUrl;
    }
Sets the application's 'unauthorized' URL to be assigned to all acquired Filters that subclass
{@link AuthorizationFilter}.  This is a convenience mechanism: for all configured {@link #setFilters filters},
as well for any default ones ({@code roles}, {@code perms}, etc.), this value will be passed on to each Filter
via the {@link AuthorizationFilter#setUnauthorizedUrl(String)} method<b>*</b>.  This eliminates the need to
configure the 'unauthorizedUrl' property manually on each filter instance, and instead that can be configured once
via this attribute.
<p/>
<b>*</b>If a filter already has already been explicitly configured with a value, it will
<em>not</em> receive this value. Individual filter configuration overrides this global convenience property.

@param unauthorizedUrl the application's 'unauthorized' URL to apply to as a convenience to all discovered
                       {@link AuthorizationFilter} instances.
@see AuthorizationFilter#setUnauthorizedUrl(String)
support/spring/src/main/java/org/apache/shiro/spring/web/ShiroFilterFactoryBean.java