Getting system metadata from a folder object (java binding)

Using the Java binding, I cannot retrieve system metadata using getSystemMetadata(), it returns an error code "The requested resource was not found on the server."

MetadataList metadata = api.getSystemMetadata(new ObjectPath("/"), null);

While it works fine with the getAllMetadata() method.

ObjectMetadata metadata = api.getAllMetadata(new ObjectPath("/"));

Isn't there a consistency issue? It seems at a first glance that the first method fires a GET request, the second a HEAD request.

Is it a bug of the Java binding?

Regards