private void initMembershipListener() {
   for (MembershipListener membershipListener : listeners.values()) {
     if (membershipListener instanceof InitialMembershipListener) {
       // TODO: needs sync with membership events...
       final Cluster cluster = client.getCluster();
       ((InitialMembershipListener) membershipListener)
           .init(new InitialMembershipEvent(cluster, cluster.getMembers()));
     }
   }
 }