docs: @RequirePOST
      public HttpRedirect doQuietDown(@QueryParameter boolean block, @QueryParameter int timeout) throws InterruptedException, IOException {
          synchronized (this) {
              checkPermission(ADMINISTER);
              isQuietingDown = true;
          }
          if (block) {
              long waitUntil = timeout;
              if (timeout > 0) waitUntil += System.currentTimeMillis();
              while (isQuietingDown
                     && (timeout <= 0 || System.currentTimeMillis() < waitUntil)
                     && !RestartListener.isAllReady()) {
                  Thread.sleep(TimeUnit.SECONDS.toMillis(1));
              }
          }
          return new HttpRedirect(".");
      }