Ingredient has this twice:

* presentation[x] and presentationText

* concentration[x] and concentrationText

SubstanceDefinition has:

* amount[x] and amountType

There may be others as well, but I'm not sure.

These are problematic for some parsers.

See the following chat for more info:

https://chat.fhir.org/#narrow/stream/179266-fhirpath/topic/Handling.20choice.20elements/near/250711383

I thought there was already a Jira open for this one, but I can't seem to find it now and I wanted to make sure this wasn't lost / forgotten.