.append("owner"       , this.getFactor_owner().toString() )
  public String toString() {    return new ToStringBuilder(this, ToStringStyle.SIMPLE_STYLE )      .append("name"        , this.getClass()                   )      .append("left"        , this.getLeft().toString()         )      .append("right"       , this.getRight().toString()        )      .toString();  } // public String toString()