Too many required attributes in json.schema

[dcorallo]

The schema ShipNavRoute.json is

{
  "type": "object",
  "description": "The routing information for the ship's most recent transit or current location.",
  "properties": {
    "destination": {
      "$ref": "./ShipNavRouteWaypoint.json"
    },
    "origin": {
      "$ref": "./ShipNavRouteWaypoint.json"
    },
    "departureTime": {
      "type": "string",
      "format": "date-time",
      "description": "The date time of the ship's departure."
    },
    "arrival": {
      "type": "string",
      "format": "date-time",
      "description": "The date time of the ship's arrival. If the ship is in-transit, this is the expected time of arrival."
    }
  },
  "required": [
    "destination",
    "departure",
    "origin",
    "departureTime",
    "arrival"
  ]
}

departure is marked as required, but not defined as a property.

Similarly, in ShipyardShip.json, symbol is required, but not a property.