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.