Top-level 'properties' not allowed

(From M. Taylor assessment [2022-01-17])

The top-level FeatureCollection object in the example has a "properties" member. This is illegal according to section 7.1 of RFC 7946:

'FeatureCollection and Geometry objects, respectively, MUST NOT contain a "geometry" or "properties" member.' In general I think it would be a good idea to use the name "properties" only for the Feature member defined in sec 3.2.1; see also my comment on sec 4 below.

If you want to provide custom metadata for a FeatureCollection I would suggest either specifying a different name for the relevant member, or just rely on the fact that Foreign Members are permitted following RFC 7946 section 6.1.