New Post endpoint for creating data elements with PATCH like response

[ivarne]

Description

Service owners want to make changes to the dataElements when attachments gets uploaded, but the current POST endpoint on DataController, does not return the updated instance.Data (with new and deleted data elements), and changed validation issues.

The proposal is for a new URL to work in addition to the previous url where the dataType is a url parameter instead of a GET parameter.

// Previous url
/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/data?dataType=xx

// New url
/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/data/{dataType}

This means that we keep backwards compatibility for current API users, but new versions of frontend can use the new url to get a richer response back.

Additional Information

Another benefit is that we can (in the future) hack into the openApi generation process and registrer special urls for all DataTypes in applicationmetadata.json so that the actual data models is exposed.