code: public Resource.Iterator get(Resource resource) {
  		Integer key = Integer.valueOf(System.identityHashCode(resource));
  		return map.get(key);
  	}
docs: Lookup the iterator associated with the given resource. If there is no
  iterator, null is returned.
  
  @param resource
  resource to use for lookup
  
  @return Resource.Iterator iterator associated with given resource or null
  if no mapping exists