Yes, Class diagram is better to be tech agonostic. You can show managed beans to make class diagram representing complete solution but do not mark it as managedbean sterotype. For example, LoginCMD can be shown in class diagram and it can be implemented as
struts action class or
JSF managed bean.
For Sequence diagrams, it is better to show all classes like managed bean, service locator, POJOs. It is better to provide all details in SD to make things clear for developers.