code: public void recordConnectionError(String trackerName) {
      synchronized (this) {
        NodeUsageReport usageReport = getReportUnprotected(trackerName);
        usageReport
            .setNumFailedConnections(usageReport.getNumFailedConnections() + 1);
      }
    }
docs: Increment the number of connection errors encountered on a tracker.
  @param trackerName The name of the tracker.