code: @Override
      public void nextTuple()
      {
          if (isRestricted() == false)
          {
              if (this.emitBuffer.isEmpty())
              {
                  tryEachKestrelUntilBufferFilled();
              }
  
              EmitItem item = this.emitBuffer.poll();
              if (item != null)
              {
                  this.collector.emit(item.getTuple(), item.getSourceId());
              }
          }
      }
docs: {@inheritDoc}