Roster, RosterGroup AddEntry bug?

I am attempting to add a current user to my roster and group. I get an exception thrown on Roster.java line 249

I have a good connection we will just call it connection for this code:

String user = “joe”;

String[] = {“Group1”, “Group2”};

connection.getRoster().createEntry(user+"@hostname.host", user, groups);

Does anyone have any ideas?