public boolean isShared() {
        return !sharedGroups.isEmpty() || !invisibleSharedGroups.isEmpty();
    }
Returns true if this item belongs to a shared group. Return true even if the item belongs
to a personal group and a shared group.

@return true if this item belongs to a shared group.
xmppserver/src/main/java/org/jivesoftware/openfire/roster/RosterItem.java