Internal reference "#" should resolve from contained resource to the container

[ewoutkramer]

This section https://www.hl7.org/fhir/references.html#contained mentions that "#" can be used in references to reference from a contained resource to its container. This should work both in the validator and the FP resolve() operation (though I don't think it needs to be supported in the minimal FP dialect used for discriminators).

(Note that the ref-1 invariant on Reference will trigger for this, still, operationally we can make it work).

[brianpos]

Careful that just # will resolve to a resource with no Id, which can create an infinite loop during validation.

[alexzautke]

Would it be possible to pre-apply the ref-1 fix as proposed here https://jira.hl7.org/browse/FHIR-31732 in R4 and make this work as proposed in the validator? The Firely Server team notices this issue during testing with data provided by a customer. No high priority issue yet, but it could be a potential issue soon.

[ewoutkramer]

Fixed by #2167.