public void addMembershipListener(MembershipListener listener){
  membershipListeners.putIfAbsent(listener,Boolean.TRUE);
}

public void addMembershipListener ( MembershipListener listener ) { membershipListeners . putIfAbsent ( listener , Boolean . TRUE ) ; }
add listener to the list to receive notification when a profile is added or removed . note that there is no guarantee that the listener will not get redundant calls , but the listener is guaranteed to get a call .
