in kinesis-taxi-stream-producer/src/main/java/com/amazonaws/flink/refarch/utils/WatermarkTracker.java [155:164]
private void removeEvent() {
inflightEvents.remove(event);
TripEvent oldestEventInQueue = inflightEvents.poll();
//determine the larges possible watermark value, this assumes that events are sent in order
if (oldestEventInQueue != null && event.timestamp < oldestEventInQueue.timestamp) {
currentWatermark = event.timestamp;
}
}