CH Core DocumentReference EPR: wrong mapping of the creation time

[qligier]

In CH Core DocumentReference EPR, date is explicitly set to required:

ch-core/input/fsh/profiles-resources/CHCoreDocumentReferenceEPR.fsh

Line 17 in 8f44876

* date 1..

This seems to be a wrong mapping from XDS, where creationTime is required. But date represents the creation time of the DocumentReference itself; the creation time of the document (what creationTime represents) is mapped to content.attachment.creation in MHD.

The cardinality of date should be reset to 0..1. The cardinality of content.attachment.creation is discussed in #320

[dvribeira]

Good, I was wondering about this one, thanks!