code: private void setLayerBuildAccessors(Set<String> buildKeys) {
  		NavigableSet<String> sorted = new TreeSet<String>(buildKeys);
  		Set<String> evictionKeys = new HashSet<String>();	// list of layer keys to remove because they
  		// have no layer builds in the layerBuildMap
  		for (Map.Entry<String, ILayer> entry : cacheMap.entrySet()) {
  			LayerImpl layer = (LayerImpl)entry.getValue();
  			LayerBuildsAccessor accessor = new LayerBuildsAccessor(layer.getId(), layerBuildMap, aggregator.getCacheManager(),  cloneLock, sorted, this);
  			if (accessor.getCount() > 0) {
  				layer.setLayerBuildsAccessor(accessor);
  			} else {
  				evictionKeys.add(entry.getKey());
  			}
  		}
  		// Now remove the layers that are missing layer builds in the layerBuildMap
  		for (String key : evictionKeys) {
  			cacheMap.remove(key);
  		}
  	}
docs: Calls setLayerBuildAccessor for each layer in <code>layerMap</code>.
  
  @param buildKeys
  Set of keys in the build map. This is not necessarily the
  same as <code>layerBuildMap.keySet()</code> because we may be
  migrating th builds to a new map in the event that the maximum
  size has changed.