How to reload Spring Security Principal after updating in Hibernate?

OK dug around and finally found the answer.

We can create a UsernamePasswordAuthenticationToken and assign the updated Principal to the context.

Authentication authentication = new UsernamePasswordAuthenticationToken(userObject, userObject.getPassword(), userObject.getAuthorities());
SecurityContextHolder.getContext().setAuthentication(authentication);

See also "How to manually set an authenticated user in Spring Security / SpringMVC".