code: protected HtmlResponse movedPermanently(HtmlResponse response) {
          assertArgumentNotNull("response", response);
          if (!response.isRedirectTo()) {
              throw new IllegalStateException("Not redirect response: " + response);
          }
          responseManager.movedPermanently(response);
          return HtmlResponse.undefined(); // because of already done about response process
      }
docs: Handle the redirect URL to be MOVED_PERMANENTLY (301 redirect). <br>
  Remove redirect mark and add header elements as 301 and return null.
  <pre>
  <span style="color: #3F7E5E">// e.g. /member/edit/</span>
  return <span style="color: #FD4747">movedPermanently</span>(redirect(MemberEditAction.class));
  </pre>
  @param response The action response of HTML to redirect. (NotNull)
  @return The empty HTML response because of response already written. (NotNull)