code: private boolean containsUpgradeHeaders(HttpRequest httpRequest) {
          HttpHeaders headers = httpRequest.headers();
          return headers.containsValue(HttpHeaderNames.CONNECTION, HttpHeaderValues.UPGRADE, true) && headers
                  .containsValue(HttpHeaderNames.UPGRADE, HttpHeaderValues.WEBSOCKET, true);
      }
docs: Check the basic headers needed for WebSocket upgrade are contained in the request.
  
  @param httpRequest {@link HttpRequest} which is checked for WebSocket upgrade.
  @return true if basic headers needed for WebSocket upgrade are contained in the request.