Required options should be marked to avoid confusion

[trobert2]

hello everyone,
I've been implementing a feature using your partner api based on the models found in this repository.

Most of the locations have the coordinates fields in them. Ex:

    {
      "location_id": 1185,
      "type": "area",
      "name": "New York (State)",
      "english_name": "New York (State)",
      "country": "US",
      "coordinates": {
        "lat": 43.2994285,
        "long": -74.2179326
      },
      "parent_id": 173303
    }

I have based my implementation off of this fact.

Then suddenly the code started to fail because of one tour ("tour_id": 109024) that could not be Unmarshalled due to the location object looking like so:

 "locations": [
    {
      "location_id": 173303,
      "type": "area",
      "name": "Hamilton County, New York",
      "english_name": "Hamilton County, New York",
      "country": "US",
      "parent_id": 168990
    }
  ],

AFAIK in openapi schema fields are optional unless marked otherwise. Properties that are required to be returned should thus be marked as such in the component schema to ensure a better experience for the users of the API