original_resource_uri in Resource is a strange type

RESOURCE_DESCRIPTION_ITEM.original_resource_uri is a List<Hash<String, String>> according to the spec. In the only examples I have where it is used, it's just a HASH<String, String>, or actually a HASH<String, URI> in ODIN syntax.

I would expect this to be the same as the example I have, or to have an explanation on why this is a list and what this list means.