public Reference addOrder() { //3
      Reference t = new Reference();
      if (this.order == null)
        this.order = new ArrayList<Reference>();
      this.order.add(t);
      return t;
    }
public Reference addOrder ( ) { Reference t = new Reference ( ) ; if ( this . order == null ) this . order = new ArrayList < Reference > ( ) ; this . order . add ( t ) ; return t ; }
syntactic sugar