code: @SuppressWarnings("unchecked")
      @Override
      protected E buildConcreteInstance(User user, Integer expirationTimeInMinutes) {
          if (expirationTimeInMinutes == null) {
              return (E) new PasswordResetToken(user);
          }
          return (E) new PasswordResetToken(user, expirationTimeInMinutes);
      }
docs: Builds a concrete instance of this class.