GrantAuthority.java

Authentication auth = SecurityContextHolder.getContext().getAuthentication();
List<GrantedAuthority> authorities = new ArrayList<GrantedAuthority>(auth.getAuthorities());
authorities.add(new SimpleGrantedAuthority("ROLE_USER"));
Authentication newAuth = new UsernamePasswordAuthenticationToken(auth.getPrincipal(), auth.getCredentials(), authorities);
SecurityContextHolder.getContext().setAuthentication(newAuth);