public Builder retry(long duration,TimeUnit timeUnit){
  this.retry=timeUnit.toSeconds(duration);
  return this;
}

public Builder retry ( long duration , TimeUnit timeUnit ) { this . retry = timeUnit . toSeconds ( duration ) ; return this ; }
set the period after which , if no ack is received , the job is put again into the queue for delivery . if retry is 0 , the job has at - most - once delivery semantics .
