Interpreting JSON as JSON-LD / Content-Type header spec. requirements

Hi list,

In am writing tests and a possibly a new async document loader
implementation for jsonld-java that could check Content-Type and Link
headers before fetching.  The current one does not.

I would like research and find actual examples where the JSON-LD
specification about the Interpretation requirement has been observed.
Anyone know a site that serve Content-Type application/json with a Link
header that provides a "http://www.w3.org/ns/json-ld#context" relation?

Also could somebody please explain to me why application/ld+json is
forbidden to provide an #context relation with a Link Header?  Is an
#context relation (if served as application/ld+json) allowed to specify a
http://www.w3.org/ns/json-ld# profile?  Or could a non
http://www.w3.org/ns/json-ld# Content-Type profile be served as
application/json and provide a secondary #context relation if it were
itself an #context ?  Should the document loader check (and possibly
dereference the relations) if "second-step" remote documents provide Link
and/or Content-Type profile?  Should there be a processing "order of
precedence"?

Just trying to understand required hypermedia options and possible use
cases.

Thanks,
Christopher Johnson
Scientific Associate
Universitätsbibliothek Leipzig

[1]
https://stackoverflow.com/questions/39551829/usage-for-profile-parameter-for-json-ld-requests
[2] https://json-ld.org/spec/latest/json-ld/#interpreting-json-as-json-ld
[3] https://github.com/IIIF/api/issues/1066