code: private boolean hasReceivedHeartbeat() {
          long currentTimeMillis = System.currentTimeMillis();
          boolean result = lastTimeMessageReceived + heartbeatTimeoutMs >= currentTimeMillis;
  
          if (!result)
              Jvm.warn().on(getClass(), Integer.toHexString(hashCode()) + " missed heartbeat, lastTimeMessageReceived=" + lastTimeMessageReceived
                      + ", currentTimeMillis=" + currentTimeMillis);
          return result;
      }
docs: called periodically to check that the heartbeat has been received
  
  @return {@code true} if we have received a heartbeat recently