add underscore to regex to be able to use underscore in URIs.

[Daare]

possible solution for issue #1886

The regexes used for validating full URLs and references are causing errors in cases where short URLs are present in a FHIR Bundle and the referenced resource has a full url that contains an underscore. Specifically, the issue arises with short references like Patient/263778 or Condition/ecde719d-4484-4093-b277-3ae90d0a2de8 and full urls like: https://rd-vm01.rd.dtcs.local/iM1AS_QO999/api/v1/fhir/Patient/263778 and https://rd-vm01.rd.dtcs.local/iM1AS_QO999/api/v1/fhir/Condition/ecde719d-4484-4093-b277-3ae90d0a2de8. In contrast when the full url is used for referencing instead of the short reference no issue occurs.

Expected Behavior:
It is possible to use a short reference to reference a resource that has a full url which contains an underscore.

[grahamegrieve]

This doesn't look valid to me

[Daare]

@grahamegrieve please elaborate

additional i have some examples which can be tried on https://validator.fhir.org/

• no_underscore_short_reference.json this one should work. it has no underscores in the full url and uses short references.
• underscore_fullUrl_reference.json this one should work too. it has underscores and uses the full url as reference.
• underscore_short_reference.json this one does not work. this has underscores and uses short urls.

[grahamegrieve]

You added _ in two places - before the Resource name, and also in the resource id. It's not valid to use _ in the id section. Also, there needs to a PR to the test cases to add passing and failing tests for this change