Clarify that the DeviceResponse schema is not mandatory

[eric-murray]

Problem description
The Design Guide states that the DeviceResponse schema should be used to disambiguate which device identifier is being used by an implementation when an API consumer has provided more than one identifier, but it does not mandate it. Nor should it, as there will be APIs for which it is not appropriate. If it is used by an API, however, then it becomes mandatory to provide a single device identifier in the response when multiple are provided in the request.

The current documentation does not make this completely clear.

Expected action
Clarify the documentation

Additional context
Many APIs do not currently allow a device to be included in the response, and forcing them to add one might lead to an overly-complicated response definition

[hdamker]

... then it becomes mandatory to provide a single device identifier in the response when multiple are provided in the response

@eric-murray I suppose you meant: "... ... then it becomes mandatory to provide a single device identifier in the response when multiple are provided in the request"

[eric-murray]

I suppose you meant: "... ... then it becomes mandatory to provide a single device identifier in the response when multiple are provided in the request"

Yes, indeed, Corrected.