fields extension includes empty "collections" attribute on Collection records

[alukach]

Using docker compose up...

▶ curl -s http://localhost:8082/collections\?fields\=id | jq .collections
[
  {
    "id": "joplin",
    "collection": null,
    "links": [
      {
        "rel": "items",
        "type": "application/geo+json",
        "href": "http://localhost:8082/api/v1/pgstac/collections/joplin/items"
      },
      {
        "rel": "parent",
        "type": "application/json",
        "href": "http://localhost:8082/api/v1/pgstac/"
      },
      {
        "rel": "root",
        "type": "application/json",
        "href": "http://localhost:8082/api/v1/pgstac/"
      },
      {
        "rel": "self",
        "type": "application/json",
        "href": "http://localhost:8082/api/v1/pgstac/collections/joplin"
      },
      {
        "rel": "http://www.opengis.net/def/rel/ogc/1.0/queryables",
        "type": "application/schema+json",
        "title": "Queryables",
        "href": "http://localhost:8082/api/v1/pgstac/collections/joplin/queryables"
      }
    ]
  }
]

[vincentsarago]

fields should not be supported TBH because there is not specification for it!