Sortable support for allowing sorting over fields not explicitly mentioned in /sortables

[philvarner]

The Queryables mechanism in CQL support uses a field additionalProperties to indicate that the server allows values to be requested that are not explicitly defined as queryables. This should also be applied to the Sortable specification, so a client may request sorting on a property that may not exist on any or all of the result entities and is not explicitly defined as a sortable field in the .../sortables endpoints.

[pvretano]

@philvarner the sortables stuff is directly derived from the queryables stuff (same schema I think) so yes, it will inherit additionalProperties=true. The link to the sortables schema in the document seems to be broken at the moment but I will fix that and verify.

[philvarner]

@pvretano ah, great. It would be nice to have something about that in the text also, since (now that I searched for it) it seems to only be described by the schemas.

[pvretano]

29-NOV-2021: The SWG agree with @philvarner and as mentioned, the sortables are derived from the queryables stuff so additionaProperty=true is already there. A related issues #126 mentions that we are moving the API stuff of records (q, sortables, etc.) to features.

[pvretano]

07-FEB-2022: The issue has been answered the question (i.e. additionalProperties=true is inherited from the queryables schema) and also referenced the issue that is moving q and sortby to features.