code: protected void gotPong (PongResponse pong)
      {
          // if we're not currently calculating our delta, then we can throw away the pong
          if (_dcalc != null) {
              // we update the delta after every receipt so as to immediately obtain an estimate of
              // the clock delta and then refine it as more packets come in
              _dcalc.gotPong(pong);
              _serverDelta = _dcalc.getTimeDelta();
          }
      }
docs: Called when we receive a pong packet. We may be in the process of calculating the client/
  server time differential, or we may have already done that at which point we ignore pongs.