docs: public void update(@Nonnull Authentication auth) throws IOException {
          List<String> roles = new ArrayList<>();
          for (GrantedAuthority ga : auth.getAuthorities()) {
              roles.add(ga.getAuthority());
          }
          String[] a = roles.toArray(new String[0]);
          if (!Arrays.equals(this.roles,a)) {
              this.roles = a;
              this.timestamp = System.currentTimeMillis();
              user.save();
          }
      }