docs: @GuardedBy("lock")
    private boolean startPendingStreams() {
      boolean hasStreamStarted = false;
      while (!pendingStreams.isEmpty() && streams.size() < maxConcurrentStreams) {
        OkHttpClientStream stream = pendingStreams.poll();
        startStream(stream);
        hasStreamStarted = true;
      }
      return hasStreamStarted;
    }