Adding an objectClass to an Entry

[Andrew Wiley]

I'm trying to figure out how to add an objectClass to an entry in the
directory, but I seem to be misunderstanding how modifications should work.
I'm trying something like this:
AttributeType attr = new AttributeType("objectClass");
Modification mod = new
ServerModification(ModificationOperation.ADD_ATTRIBUTE, new
DefaultServerAttribute(attr, "javaObject"));

The problem is that attr.getSyntax() is returning null, but I'm not sure
what the AttributeType should be if not objectClass. How should I be doing
this?

Any help is appreciated,
Andrew Wiley