code: public synchronized void onTransportIdle() {
      if (keepAliveDuringTransportIdle) {
        return;
      }
      if (state == State.PING_SCHEDULED || state == State.PING_DELAYED) {
        state = State.IDLE;
      }
      if (state == State.PING_SENT) {
        state = State.IDLE_AND_PING_SENT;
      }
    }
docs: Transport has finished all streams.