if (base == null) throw new IllegalArgumentException ("null input: base");
final IdentityHashMap visited = new IdentityHashMap ();
computeSizeof (base, visited, CLASS_METADATA_CACHE);
return visited.containsKey (obj) ? 0 : computeSizeof (obj, visited, CLASS_METADATA_CACHE);
}
/**
* Creates a spanning tree representation for instance data contained in
* 'obj'. The tree is produced using bread-first traversal over the full