src/main/java/org/jivesoftware/smack/RosterEntry.java
public Collection<RosterGroup> getGroups() {
        List<RosterGroup> results = new ArrayList<RosterGroup>();
        // Loop through all roster groups and find the ones that contain this
        // entry. This algorithm should be fine
        for (RosterGroup group : roster.getGroups()) {
            if (group.contains(this)) {
                results.add(group);
            }
        }
        return Collections.unmodifiableCollection(results);
    }
public Collection<RosterGroup> getGroups() {
        List<RosterGroup> results = new ArrayList<RosterGroup>();
        // Loop through all roster groups and find the ones that contain this
        // entry. This algorithm should be fine
        for (RosterGroup group : roster.getGroups()) {
            if (group.contains(this)) {
                results.add(group);
            }
        }
        return Collections.unmodifiableCollection(results);
    }
Returns an unmodifiable collection of the roster groups that this entry
belongs to.

@return an iterator for the groups this entry belongs to.