toString(resources, sb) in Configuration.java throws a ClassCastException since resources can be loaded from an URL

Object obj = i.next();
if (obj instanceof Path) {
sb.append((Path)obj);
} else {
sb.append((String)obj);
}

If obj is an URL -> ClassCastException.

Moreover, I think the test before appending the resource to the StringBuffer is not really necessary since the method take an Object as argument. Why not simply have :

Object obj = i.next();
sb.append(obj);

I have attached a patch to fix this.