code: @Override
      public void handleWriteFailure(final ApnsClient apnsClient, final long notificationId) {
          this.notificationStartTimes.remove(notificationId);
          this.writeFailures.increment();
      }
docs: Records a failed attempt to send a notification and updates metrics accordingly.
  
  @param apnsClient the client that failed to write the notification; note that this is ignored by
  {@code MicrometerApnsClientMetricsListener} instances, which should always be used for exactly one client
  @param notificationId an opaque, unique identifier for the notification that could not be written