@Override
  protected void process(ClusterDistributionManager dm) {
    // do nothing. We are just pinging the server. send the reply back.
    ReplyMessage.send(getSender(), processorId, null, dm);
  }
Sends a ping message. The pre-GFXD_101 recipients are filtered out and it is assumed that they
are pingable.

@return true if all the recipients are pingable
geode-core/src/main/java/org/apache/geode/internal/cache/ServerPingMessage.java