Supporting FML transforms between different FHIR versions

[oliveregger]

We would like to support conversion between different FHIR versions.

see also zulip thread here

e.g. convert between R4 and R5 (or to future R6)

see also writeup from brian here: https://hackmd.io/I_li7rJwTGCehzmtQ0xSMw

HL7 provides the FHIR Cross-Version Mapping Pack as an IG: https://build.fhir.org/ig/HL7/fhir-cross-version/artifacts.html

The approach to follow is here:
https://github.com/hapifhir/org.hl7.fhir.core/blob/master/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/conversion/tests/R3R4ConversionTests.java#L300

[oliveregger]

the above cross version package includes maps for the different releases, but can't find the references concept maps inside (correction: the concept maps are in the codes folder: e.g.: https://github.com/HL7/fhir-cross-version/blob/main/input/codes/ConceptMap-Age-4bto4.json, however they are not listed in the artifact page)

the validator currently uses another package https://simplifier.net/packages/hl7.fhir.xver.r4/1.2.0/~files where the StructureDefintions are directly provided with the version inside e.g. /4.0. but the version r5 is not included there. also maps for r4 to r5 are not included.

[oliveregger]

see also gino's documentation for xver:
https://github.com/GinoCanessa/fhir-cross-version-source and https://hackmd.io/nynfO0LWQm6qntjnzap2bQ

[oliveregger]

brian works on fixing the maps in this branch: https://github.com/HL7/fhir-cross-version/tree/BP-structuremap-missed-props

[oliveregger]

initial version, need to configure it in application.yaml with xVersion: true, added in version 3.9.0