private void sendPing() {
    // we store the timestamp when we sent the ping
    pingTimestamp = System.currentTimeMillis();

    sendMessage(
        webSocket,
        new EthStatsRequest(
            NODE_PING,
            ImmutablePingReport.of(
                enodeURL.getNodeId().toHexString(), String.valueOf(pingTimestamp))));
  }
Sends a ping request to the ethstats server
ethereum/ethstats/src/main/java/org/hyperledger/besu/ethstats/EthStatsService.java