static final HashMap<Resource, HashMap<Integer, Permission>> buildRegistry(
final Collection<? extends Permission> permissions) {
final HashMap<Resource, HashMap<Integer, Permission>> registry = new HashMap<>();
for (final Permission permission : permissions) {
HashMap<Integer, Permission> map = registry.get(permission.resource());
if (map == null) {
registry.put(permission.resource(), map = new HashMap<>());
}
map.put(permission.factor(), permission);
}
return registry;
}
