public ServerAddress address(){
  AtomicReference<ServerAddress> address=new AtomicReference<>();
  execute("get replica set primary",null);
  return address.get();
}

public ServerAddress address ( ) { AtomicReference < ServerAddress > address = new AtomicReference < > ( ) ; execute ( "get replica set primary" , null ) ; return address . get ( ) ; }
get the address of the primary node , if there is one .
