code: public void stop() {
          if (isStarted()) {
              log.info("Stopping browser " + webDriver.getCurrentUrl());
  
              try {
                  log.info("Trying to close the browser " + webDriver + " ...");
                  webDriver.quit();
              } catch (UnreachableBrowserException e) {
                  // It happens for Firefox. It's ok: browser is already closed.
                  log.warn("Browser is unreachable", e);
              } catch (WebDriverException e) {
                  log.error("Failed to close browser", e);
              }
  
              webDriver = null;
          } else {
              log.warn("Browser already stopped");
          }
      }
docs: Stop the browser when started.