code: private final boolean collision(Map<Object, InvalidationEvent> hashtable, Enumeration enumeration, long timeStamp) {
  		while (enumeration.hasMoreElements()) {
  			Object key = enumeration.nextElement();	
  			InvalidationEvent invalidationEvent = (InvalidationEvent) hashtable.get(key);	
  			if ((invalidationEvent != null) && (invalidationEvent.getTimeStamp() > timeStamp)) {
  				return true;
  			}
  		}
  		return false;
  	}
docs: This is a helper method that checks for a collision.
  
  @param hashtable A Hashtable of invalidation events.
  @param enumeration An Enumeration of
  @return True if there is an item in the enumeration
  that is specified in the hashtable such that
  the hashtable entry is newer than the timeStamp.