Requires the current Subject to be a "guest", that is, they are not authenticated <em>or</em> remembered from a previous session for the annotated class/instance/method to be accessed or invoked. <p/> This annotation is the logical inverse of the {@link RequiresUser RequiresUser} annotation. That is, <code>RequiresUser == !RequiresGuest</code>, or more accurately, <p/> <code>RequiresGuest === subject.{@link hunt.shiro.subject.Subject#getPrincipal() getPrincipal()} is null</code>.