public TSink<String> sendString(TStream<String> stream){
  Objects.requireNonNull(stream,"stream");
  return sendText(stream,null);
}

public TSink < String > sendString ( TStream < String > stream ) { Objects . requireNonNull ( stream , "stream" ) ; return sendText ( stream , null ) ; }
send a stream ' s string tuples in a websocket text message .
