Map<Class, AssetFactory> byResourceClass = newMap();
for (Map.Entry<String, AssetFactory> e : configuration.entrySet())
{
String prefix = e.getKey();
AssetFactory factory = e.getValue();
Resource rootResource = factory.getRootResource();
byResourceClass.put(rootResource.getClass(), factory);
_prefixToRootResource.put(prefix, rootResource);
}