code: public void ping() {
          long newPingTime = System.currentTimeMillis();
          if (log.isDebugEnabled()) {
              log.debug("Send Ping: session=[{}], currentTime=[{}], lastPingTime=[{}]", new Object[] { getSessionId(), newPingTime, lastPingSentOn.get() });
          }
          if (lastPingSentOn.get() == 0) {
              lastPongReceivedOn.set(newPingTime);
          }
          Ping pingRequest = new Ping();
          pingRequest.setEventType(Ping.PING_CLIENT);
          lastPingSentOn.set(newPingTime);
          int now = (int) (newPingTime & 0xffffffffL);
          pingRequest.setValue2(now);
          ping(pingRequest);
      }
docs: {@inheritDoc}