code: protected boolean beginRequest() {
          int oldState, newState;
          for (;;) {
              oldState = state;
              if ((oldState & CLOSED) != 0) {
                  return false;
              }
              newState = oldState + 1;
              if (newState == Integer.MAX_VALUE) {
                  return false;
              }
              if (stateUpdater.compareAndSet(this, oldState, newState)) {
                  return true;
              }
          }
      }
docs: This gets called when we receive a new http mgmt request and returns whether
  the request can process or should return a {@code 503} response when the server
  is about to shutdown.
  
  @return {@code true} if the request can be processed; {@code false} if the server is about to shut down