docs: public Iterable<DesiredCapabilities> getDesiredCapabilities() {
      lock.readLock().lock();
      try {
        return newSessionRequests.stream()
            .map(req -> new DesiredCapabilities(req.getRequest().getDesiredCapabilities()))
            .collect(Collectors.toList());
      } finally {
        lock.readLock().unlock();
      }
    }