code: public void purgeCounters(final long epochMinute)
      {
      	for (Iterator<Map.Entry<String, MinuteCounter>> it = errorCounter.entrySet().iterator(); it.hasNext(); ) {
      		Map.Entry<String, MinuteCounter> entry = it.next();
      		
      		if (entry.getValue().getEpochMinute() < epochMinute) {
      			it.remove();
      		}
      	}
      }
docs: Purges the errorCounter map of expired entries
  @param epochMinute The current time