anchor.diff:            "opponent_fleet_type": practicePlan.opponentFleetType,
             "fleet_name": practicePlan.fleetName,
             "formation": practicePlan.formation,
  +        }).toList(),
  +      },
  +      "mission_prefs": {
  +        "mission_plans": missionPrefs.missionPlans.map((missionPlan) => {
  +          "fleet_id": missionPlan.fleetId,
  +          "mission_id": missionPlan.missionId,
           }).toList(),
         },
       });
  
positive.code:       new ObservableList<PracticePlan>();
  }
  
  class Preferences extends Observable {
    @observable AutomanPrefs automanPrefs = new AutomanPrefs();
    @observable FleetPrefs fleetPrefs = new FleetPrefs();
    @observable PracticePrefs practicePrefs = new PracticePrefs();
  
    // Convert this preferences object to JSON so that the server can directly
    // accept it as the Prefenreces object.
  
negative.code:         practicePlan["formation"]);
      prefs.practicePrefs.practicePlans.add(practicePlanObject);
    }
    for (var missionPlan in data["mission_prefs"]["mission_plans"]) {
      MissionPlan missionPlanObject = new MissionPlan(
          missionPlan["fleet_id"],
          missionPlan["mission_id"]);
      prefs.missionPrefs.missionPlans.add(missionPlanObject);
    }
    model.preferences = prefs;
  }
  