anchor.diff:    }
   }
   
  -class ShipPropertyFilter {
  +class ShipPropertyFilter extends Observable {
     @observable String property;
     @observable dynamic value;
     @observable int operator;
  
positive.code:   }
  }
  
  class ShipFilter {
    ShipFilter.fromJSON(Map<String, dynamic> data) {
    }
  
  
negative.code:       ship.belongingFleet = null;
      }
    }
  }
  